

<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.trimascorp.com/role/Acquisitions" xlink:href="trs-20180930.xsd#Acquisitions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/AcquisitionsOtherAcquisitionsDetails" xlink:href="trs-20180930.xsd#AcquisitionsOtherAcquisitionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/BasisOfPresentation" xlink:href="trs-20180930.xsd#BasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingencies" xlink:href="trs-20180930.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingenciesAsbestosClaimantAndSettlementDetails" xlink:href="trs-20180930.xsd#CommitmentsAndContingenciesAsbestosClaimantAndSettlementDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingenciesAsbestosDamagesSoughtDetails" xlink:href="trs-20180930.xsd#CommitmentsAndContingenciesAsbestosDamagesSoughtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingenciesAsbestosNarrativeDetails" xlink:href="trs-20180930.xsd#CommitmentsAndContingenciesAsbestosNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingenciesCommitmentsAndContingenciesTables" xlink:href="trs-20180930.xsd#CommitmentsAndContingenciesCommitmentsAndContingenciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingenciesMetaldyneDetails" xlink:href="trs-20180930.xsd#CommitmentsAndContingenciesMetaldyneDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsAndContingenciesOrdinaryCourseClaimsDetails" xlink:href="trs-20180930.xsd#CommitmentsAndContingenciesOrdinaryCourseClaimsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedBalanceSheetParentheticals" xlink:href="trs-20180930.xsd#ConsolidatedBalanceSheetParentheticals" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedBalanceSheetStatement" xlink:href="trs-20180930.xsd#ConsolidatedBalanceSheetStatement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementOfCashFlowsStatement" xlink:href="trs-20180930.xsd#ConsolidatedStatementOfCashFlowsStatement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementOfComprehensiveIncome" xlink:href="trs-20180930.xsd#ConsolidatedStatementOfComprehensiveIncome" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementOfIncomeStatement" xlink:href="trs-20180930.xsd#ConsolidatedStatementOfIncomeStatement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementOfShareholdersEquityStatement" xlink:href="trs-20180930.xsd#ConsolidatedStatementOfShareholdersEquityStatement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlans" xlink:href="trs-20180930.xsd#DefinedBenefitPlans" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:href="trs-20180930.xsd#DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:href="trs-20180930.xsd#DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansTables" xlink:href="trs-20180930.xsd#DefinedBenefitPlansTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstruments" xlink:href="trs-20180930.xsd#DerivativeInstruments" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativeNarrativeDetails" xlink:href="trs-20180930.xsd#DerivativeInstrumentsDerivativeNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedAsHedgingFinancialPerformanceDetails" xlink:href="trs-20180930.xsd#DerivativeInstrumentsDesignatedAsHedgingFinancialPerformanceDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedAsHedgingFinancialPerformanceNarrativeDetails" xlink:href="trs-20180930.xsd#DerivativeInstrumentsDesignatedAsHedgingFinancialPerformanceNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedAsHedgingFinancialPositionDetails" xlink:href="trs-20180930.xsd#DerivativeInstrumentsDesignatedAsHedgingFinancialPositionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsFairValueMeasurementsDetails" xlink:href="trs-20180930.xsd#DerivativeInstrumentsFairValueMeasurementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsTables" xlink:href="trs-20180930.xsd#DerivativeInstrumentsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/DocumentAndEntityInformationDocument" xlink:href="trs-20180930.xsd#DocumentAndEntityInformationDocument" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsPerShare" xlink:href="trs-20180930.xsd#EarningsPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsPerShareEarningsPerShareDetails" xlink:href="trs-20180930.xsd#EarningsPerShareEarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsPerShareEarningsPerShareTables" xlink:href="trs-20180930.xsd#EarningsPerShareEarningsPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsPerShareRepurchaseOfCommonStockDetails" xlink:href="trs-20180930.xsd#EarningsPerShareRepurchaseOfCommonStockDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwards" xlink:href="trs-20180930.xsd#EquityAwards" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsEquityAwardsNarrativeDetails" xlink:href="trs-20180930.xsd#EquityAwardsEquityAwardsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:href="trs-20180930.xsd#EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:href="trs-20180930.xsd#EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionActivityTableDetails" xlink:href="trs-20180930.xsd#EquityAwardsStockOptionActivityTableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails" xlink:href="trs-20180930.xsd#EquityAwardsStockOptionsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsTables" xlink:href="trs-20180930.xsd#EquityAwardsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityOfferingDetails" xlink:href="trs-20180930.xsd#EquityOfferingDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityOfferingNotes" xlink:href="trs-20180930.xsd#EquityOfferingNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityOfferingTables" xlink:href="trs-20180930.xsd#EquityOfferingTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/FacilityClosuresNarrativeDetails" xlink:href="trs-20180930.xsd#FacilityClosuresNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/FacilityClosuresRestructuringAndRelatedActivitiesDisclosureNotes" xlink:href="trs-20180930.xsd#FacilityClosuresRestructuringAndRelatedActivitiesDisclosureNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssets" xlink:href="trs-20180930.xsd#GoodwillAndOtherIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsGoodwillAndOtherIntangibleAssetsTables" xlink:href="trs-20180930.xsd#GoodwillAndOtherIntangibleAssetsGoodwillAndOtherIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:href="trs-20180930.xsd#GoodwillAndOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsScheduleOfFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:href="trs-20180930.xsd#GoodwillAndOtherIntangibleAssetsScheduleOfFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassDetails" xlink:href="trs-20180930.xsd#GoodwillAndOtherIntangibleAssetsScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/Inventories" xlink:href="trs-20180930.xsd#Inventories" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/InventoriesDetails" xlink:href="trs-20180930.xsd#InventoriesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/InventoriesTables" xlink:href="trs-20180930.xsd#InventoriesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebt" xlink:href="trs-20180930.xsd#LongTermDebt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebtCreditAgreementDetails" xlink:href="trs-20180930.xsd#LongTermDebtCreditAgreementDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebtDebtTableDetails" xlink:href="trs-20180930.xsd#LongTermDebtDebtTableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebtFairValueDetails" xlink:href="trs-20180930.xsd#LongTermDebtFairValueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebtLongTermDebtTables" xlink:href="trs-20180930.xsd#LongTermDebtLongTermDebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebtReceivablesFacilityDetails" xlink:href="trs-20180930.xsd#LongTermDebtReceivablesFacilityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongTermDebtSeniorNotesDetails" xlink:href="trs-20180930.xsd#LongTermDebtSeniorNotesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/NewAccountingPronouncements" xlink:href="trs-20180930.xsd#NewAccountingPronouncements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/NewAccountingPronouncementsNewAccountingPronouncementsDetails" xlink:href="trs-20180930.xsd#NewAccountingPronouncementsNewAccountingPronouncementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossDetails" xlink:href="trs-20180930.xsd#OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossNotes" xlink:href="trs-20180930.xsd#OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossTables" xlink:href="trs-20180930.xsd#OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyAndEquipmentNet" xlink:href="trs-20180930.xsd#PropertyAndEquipmentNet" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyAndEquipmentNetDepreciationExpenseTableDetails" xlink:href="trs-20180930.xsd#PropertyAndEquipmentNetDepreciationExpenseTableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyAndEquipmentNetPropertyAndEquipmentTableDetails" xlink:href="trs-20180930.xsd#PropertyAndEquipmentNetPropertyAndEquipmentTableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyAndEquipmentNetTables" xlink:href="trs-20180930.xsd#PropertyAndEquipmentNetTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueRevenueDetails" xlink:href="trs-20180930.xsd#RevenueRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueRevenueNotes" xlink:href="trs-20180930.xsd#RevenueRevenueNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueRevenuePolicies" xlink:href="trs-20180930.xsd#RevenueRevenuePolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueRevenueTables" xlink:href="trs-20180930.xsd#RevenueRevenueTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentInformation" xlink:href="trs-20180930.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentInformationSegmentInformationDetails" xlink:href="trs-20180930.xsd#SegmentInformationSegmentInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentInformationSegmentInformationTables" xlink:href="trs-20180930.xsd#SegmentInformationSegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventDetails" xlink:href="trs-20180930.xsd#SubsequentEventDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventNotes" xlink:href="trs-20180930.xsd#SubsequentEventNotes" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/Acquisitions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/AcquisitionsOtherAcquisitionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_51CC183CF7C94AFCED12AFF2BE8B98E4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_817FCDA5C37F54E3F22AAFF2BE8B2E4D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_51CC183CF7C94AFCED12AFF2BE8B98E4" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_817FCDA5C37F54E3F22AAFF2BE8B2E4D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_F7E5DF7646447D86E3D8AFF2BE8B7340" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_817FCDA5C37F54E3F22AAFF2BE8B2E4D" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_F7E5DF7646447D86E3D8AFF2BE8B7340" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4C7C1F188E86BB76C9A2AFF2BE8B9DA0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_F7E5DF7646447D86E3D8AFF2BE8B7340" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4C7C1F188E86BB76C9A2AFF2BE8B9DA0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4C7C1F188E86BB76C9A2AFF2BE8B9DA0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_F7E5DF7646447D86E3D8AFF2BE8B7340" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4C7C1F188E86BB76C9A2AFF2BE8B9DA0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_D809BDFC9672C16AABA5AFF2BE8BE590" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_51CC183CF7C94AFCED12AFF2BE8B98E4" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_D809BDFC9672C16AABA5AFF2BE8BE590" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/BasisOfPresentation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingenciesAsbestosClaimantAndSettlementDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_306386BEF5A7D5ED1836AFF2C09B8FBC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_us-gaap_LossContingenciesTable_306386BEF5A7D5ED1836AFF2C09B8FBC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_2AF9BAC1FC713AE78EF9AFF2C09B7C61" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_306386BEF5A7D5ED1836AFF2C09B8FBC" xlink:to="loc_us-gaap_LitigationStatusAxis_2AF9BAC1FC713AE78EF9AFF2C09B7C61" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_728999ED1FB70BEE3999AFF2C09BF92C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_2AF9BAC1FC713AE78EF9AFF2C09B7C61" xlink:to="loc_us-gaap_LitigationStatusDomain_728999ED1FB70BEE3999AFF2C09BF92C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_728999ED1FB70BEE3999AFF2C09BF92C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_2AF9BAC1FC713AE78EF9AFF2C09B7C61" xlink:to="loc_us-gaap_LitigationStatusDomain_728999ED1FB70BEE3999AFF2C09BF92C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PendingLitigationMember" xlink:label="loc_us-gaap_PendingLitigationMember_7F1011F2AA36BA9EB26AAFF2C09BDFCC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_728999ED1FB70BEE3999AFF2C09BF92C" xlink:to="loc_us-gaap_PendingLitigationMember_7F1011F2AA36BA9EB26AAFF2C09BDFCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_BEADA56DB19E55C36169AFF2C09BA477" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_306386BEF5A7D5ED1836AFF2C09B8FBC" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_BEADA56DB19E55C36169AFF2C09BA477" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_82A5809375813EFF469AAFF2C09BAD60_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_BEADA56DB19E55C36169AFF2C09BA477" xlink:to="loc_us-gaap_LossContingencyNatureDomain_82A5809375813EFF469AAFF2C09BAD60_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_82A5809375813EFF469AAFF2C09BAD60" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_BEADA56DB19E55C36169AFF2C09BA477" xlink:to="loc_us-gaap_LossContingencyNatureDomain_82A5809375813EFF469AAFF2C09BAD60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AsbestosIssueMember" xlink:label="loc_us-gaap_AsbestosIssueMember_32E945E0FAB0C63AA067AFF2C09B123E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_82A5809375813EFF469AAFF2C09BAD60" xlink:to="loc_us-gaap_AsbestosIssueMember_32E945E0FAB0C63AA067AFF2C09B123E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyPendingClaimsNumber" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_145271C1D0CD6157FB70AFF2C0AB6249" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_145271C1D0CD6157FB70AFF2C0AB6249" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNewClaimsFiledNumber" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_EADED343887F08868D9CAFF2C0ABD8FA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_EADED343887F08868D9CAFF2C0ABD8FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyClaimsDismissedNumber" xlink:label="loc_us-gaap_LossContingencyClaimsDismissedNumber_CFCAFB44D298D3F167CCAFF2C0AB3F01" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_us-gaap_LossContingencyClaimsDismissedNumber_CFCAFB44D298D3F167CCAFF2C0AB3F01" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyClaimsSettledNumber" xlink:label="loc_us-gaap_LossContingencyClaimsSettledNumber_12EF87D169DEC81053B4AFF2C0AB595B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_us-gaap_LossContingencyClaimsSettledNumber_12EF87D169DEC81053B4AFF2C0AB595B" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_LossContingencySettlementAgreementAverageConsideration" xlink:label="loc_trs_LossContingencySettlementAgreementAverageConsideration_4AD591D5D4C15CED3026AFF2C0ABD3D3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_trs_LossContingencySettlementAgreementAverageConsideration_4AD591D5D4C15CED3026AFF2C0ABD3D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaap_LegalFees_EC2D89249222F70E137AAFF2C0AB512D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E2648E7B79F599724E73AFF2C0AB38B9" xlink:to="loc_us-gaap_LegalFees_EC2D89249222F70E137AAFF2C0AB512D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingenciesAsbestosDamagesSoughtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_A17A99F655D533BD1239AFF2C176A127" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_A17A99F655D533BD1239AFF2C176A127" xlink:to="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_1AF36EA4EBC305ECBD68AFF2C176B951" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_1AF36EA4EBC305ECBD68AFF2C176B951" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_8296316F6AEE7CCED598AFF2C176BD4E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_1AF36EA4EBC305ECBD68AFF2C176B951" xlink:to="loc_us-gaap_LossContingencyNatureDomain_8296316F6AEE7CCED598AFF2C176BD4E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_8296316F6AEE7CCED598AFF2C176BD4E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_1AF36EA4EBC305ECBD68AFF2C176B951" xlink:to="loc_us-gaap_LossContingencyNatureDomain_8296316F6AEE7CCED598AFF2C176BD4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AsbestosIssueMember" xlink:label="loc_us-gaap_AsbestosIssueMember_09104AAADD6B95DB8824AFF2C176DAC6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_8296316F6AEE7CCED598AFF2C176BD4E" xlink:to="loc_us-gaap_AsbestosIssueMember_09104AAADD6B95DB8824AFF2C176DAC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_13507C7F71314081C059AFF2C176753B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:to="loc_us-gaap_LitigationStatusAxis_13507C7F71314081C059AFF2C176753B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_7C21D71AC61E8CA808A8AFF2C176D493_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_13507C7F71314081C059AFF2C176753B" xlink:to="loc_us-gaap_LitigationStatusDomain_7C21D71AC61E8CA808A8AFF2C176D493_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_7C21D71AC61E8CA808A8AFF2C176D493" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_13507C7F71314081C059AFF2C176753B" xlink:to="loc_us-gaap_LitigationStatusDomain_7C21D71AC61E8CA808A8AFF2C176D493" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PendingLitigationMember" xlink:label="loc_us-gaap_PendingLitigationMember_1C7F4ABB6D0EE9825378AFF2C1763473" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_7C21D71AC61E8CA808A8AFF2C176D493" xlink:to="loc_us-gaap_PendingLitigationMember_1C7F4ABB6D0EE9825378AFF2C1763473" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtTypeAxis" xlink:label="loc_trs_DamagesSoughtTypeAxis_16299585A5E6C22AB68BAFF2C176CB00" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:to="loc_trs_DamagesSoughtTypeAxis_16299585A5E6C22AB68BAFF2C176CB00" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtTypeDomain" xlink:label="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_16299585A5E6C22AB68BAFF2C176CB00" xlink:to="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B_default" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtTypeDomain" xlink:label="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_16299585A5E6C22AB68BAFF2C176CB00" xlink:to="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_CompensatoryAndPunitiveDamagesMember" xlink:label="loc_trs_CompensatoryAndPunitiveDamagesMember_58899C3B6EF238CAD4CFAFF2C176E4BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B" xlink:to="loc_trs_CompensatoryAndPunitiveDamagesMember_58899C3B6EF238CAD4CFAFF2C176E4BD" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_CompensatoryOnlyDamagesMember" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_21F9AC67323F923C7BC5AFF2C176E699" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_21F9AC67323F923C7BC5AFF2C176E699" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_PunitiveOnlyDamagesMember" xlink:label="loc_trs_PunitiveOnlyDamagesMember_9B367199566520B2D935AFF2C1767262" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_7E800549ACE4787CF40AAFF2C176851B" xlink:to="loc_trs_PunitiveOnlyDamagesMember_9B367199566520B2D935AFF2C1767262" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtRangeAxis" xlink:label="loc_trs_DamagesSoughtRangeAxis_B96D2B22A338EF542DADAFF2C1766ACC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:to="loc_trs_DamagesSoughtRangeAxis_B96D2B22A338EF542DADAFF2C1766ACC" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtDomain" xlink:label="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtRangeAxis_B96D2B22A338EF542DADAFF2C1766ACC" xlink:to="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC_default" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtDomain" xlink:label="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtRangeAxis_B96D2B22A338EF542DADAFF2C1766ACC" xlink:to="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Range1Member" xlink:label="loc_trs_Range1Member_45CEB00FB9F9163F17C5AFF2C176AF95" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC" xlink:to="loc_trs_Range1Member_45CEB00FB9F9163F17C5AFF2C176AF95" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Range2Member" xlink:label="loc_trs_Range2Member_BA76846897E3F9249500AFF2C1769726" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC" xlink:to="loc_trs_Range2Member_BA76846897E3F9249500AFF2C1769726" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Range3Member" xlink:label="loc_trs_Range3Member_6440FEE2EA90740A0338AFF2C176BF1D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_7C7C71A8107D2FFA276DAFF2C1764AEC" xlink:to="loc_trs_Range3Member_6440FEE2EA90740A0338AFF2C176BF1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_FA3333B2F78FC7AD831DAFF2C1761AD9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_20CA06728388F2F7E029AFF2C1769317" xlink:to="loc_srt_RangeAxis_FA3333B2F78FC7AD831DAFF2C1761AD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_89AE0A6F61973558EC59AFF2C176D106_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_FA3333B2F78FC7AD831DAFF2C1761AD9" xlink:to="loc_srt_RangeMember_89AE0A6F61973558EC59AFF2C176D106_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_89AE0A6F61973558EC59AFF2C176D106" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_FA3333B2F78FC7AD831DAFF2C1761AD9" xlink:to="loc_srt_RangeMember_89AE0A6F61973558EC59AFF2C176D106" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_B3089A4CDC590F9BFA29AFF2C176BA8A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_89AE0A6F61973558EC59AFF2C176D106" xlink:to="loc_srt_MinimumMember_B3089A4CDC590F9BFA29AFF2C176BA8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_76FA65043F9CA41044A8AFF2C17642C9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_89AE0A6F61973558EC59AFF2C176D106" xlink:to="loc_srt_MaximumMember_76FA65043F9CA41044A8AFF2C17642C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_F943A6C6CD8C166723B6AFF2C176CA5F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_A17A99F655D533BD1239AFF2C176A127" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_F943A6C6CD8C166723B6AFF2C176CA5F" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_EEBC2C0C94C21AA879AFAFF2C176ADE4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_A17A99F655D533BD1239AFF2C176A127" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_EEBC2C0C94C21AA879AFAFF2C176ADE4" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingenciesAsbestosNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseAxis" xlink:label="loc_srt_LitigationCaseAxis_5DBDEA9357B06EA4391EAFF2BEF88244" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:to="loc_srt_LitigationCaseAxis_5DBDEA9357B06EA4391EAFF2BEF88244" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_441C78EAAC87ED8BBF92AFF2BEF8BB2B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_5DBDEA9357B06EA4391EAFF2BEF88244" xlink:to="loc_srt_LitigationCaseTypeDomain_441C78EAAC87ED8BBF92AFF2BEF8BB2B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_441C78EAAC87ED8BBF92AFF2BEF8BB2B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_5DBDEA9357B06EA4391EAFF2BEF88244" xlink:to="loc_srt_LitigationCaseTypeDomain_441C78EAAC87ED8BBF92AFF2BEF8BB2B" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtTypeAxis" xlink:label="loc_trs_DamagesSoughtTypeAxis_3C92F8B2B51D570D8003AFF2BEF8FFEE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:to="loc_trs_DamagesSoughtTypeAxis_3C92F8B2B51D570D8003AFF2BEF8FFEE" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtTypeDomain" xlink:label="loc_trs_DamagesSoughtTypeDomain_51EDFC0553E38A4A0A15AFF2BEF8AF83_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_3C92F8B2B51D570D8003AFF2BEF8FFEE" xlink:to="loc_trs_DamagesSoughtTypeDomain_51EDFC0553E38A4A0A15AFF2BEF8AF83_default" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DamagesSoughtTypeDomain" xlink:label="loc_trs_DamagesSoughtTypeDomain_51EDFC0553E38A4A0A15AFF2BEF8AF83" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_3C92F8B2B51D570D8003AFF2BEF8FFEE" xlink:to="loc_trs_DamagesSoughtTypeDomain_51EDFC0553E38A4A0A15AFF2BEF8AF83" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_PunitiveOnlyDamagesMember" xlink:label="loc_trs_PunitiveOnlyDamagesMember_8C75BE2E20D66B6F8A32AFF2BEF8DA53" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_51EDFC0553E38A4A0A15AFF2BEF8AF83" xlink:to="loc_trs_PunitiveOnlyDamagesMember_8C75BE2E20D66B6F8A32AFF2BEF8DA53" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_CompensatoryOnlyDamagesMember" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_9BF79C6943BA0214FC80AFF2BEF8176E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_51EDFC0553E38A4A0A15AFF2BEF8AF83" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_9BF79C6943BA0214FC80AFF2BEF8176E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_3E94A35372F11261E01AAFF2BEF89A20" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_3E94A35372F11261E01AAFF2BEF89A20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_C3B1EEE59AFE95753FDBAFF2BEF8F9CD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_3E94A35372F11261E01AAFF2BEF89A20" xlink:to="loc_us-gaap_LossContingencyNatureDomain_C3B1EEE59AFE95753FDBAFF2BEF8F9CD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_C3B1EEE59AFE95753FDBAFF2BEF8F9CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_3E94A35372F11261E01AAFF2BEF89A20" xlink:to="loc_us-gaap_LossContingencyNatureDomain_C3B1EEE59AFE95753FDBAFF2BEF8F9CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AsbestosIssueMember" xlink:label="loc_us-gaap_AsbestosIssueMember_88191607CE1B7727E589AFF2BEF8ED42" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_C3B1EEE59AFE95753FDBAFF2BEF8F9CD" xlink:to="loc_us-gaap_AsbestosIssueMember_88191607CE1B7727E589AFF2BEF8ED42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_5053FA7A4953379CEF73AFF2BEF812B5" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:to="loc_us-gaap_LitigationStatusAxis_5053FA7A4953379CEF73AFF2BEF812B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_E5C4F06B3C3873EB9193AFF2BEF8B792_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_5053FA7A4953379CEF73AFF2BEF812B5" xlink:to="loc_us-gaap_LitigationStatusDomain_E5C4F06B3C3873EB9193AFF2BEF8B792_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_E5C4F06B3C3873EB9193AFF2BEF8B792" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_5053FA7A4953379CEF73AFF2BEF812B5" xlink:to="loc_us-gaap_LitigationStatusDomain_E5C4F06B3C3873EB9193AFF2BEF8B792" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PendingLitigationMember" xlink:label="loc_us-gaap_PendingLitigationMember_BFEB942323B506F65FD2AFF2BEF805AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_E5C4F06B3C3873EB9193AFF2BEF8B792" xlink:to="loc_us-gaap_PendingLitigationMember_BFEB942323B506F65FD2AFF2BEF805AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_B3C11B5937F7D6644B6DAFF2BEF8A5DD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_B68CFD71B9EC932CB23BAFF2BEF8CE23" xlink:to="loc_srt_RangeAxis_B3C11B5937F7D6644B6DAFF2BEF8A5DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_47C4BAAE1DD352A07344AFF2BEF875FE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_B3C11B5937F7D6644B6DAFF2BEF8A5DD" xlink:to="loc_srt_RangeMember_47C4BAAE1DD352A07344AFF2BEF875FE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_47C4BAAE1DD352A07344AFF2BEF875FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_B3C11B5937F7D6644B6DAFF2BEF8A5DD" xlink:to="loc_srt_RangeMember_47C4BAAE1DD352A07344AFF2BEF875FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_E929CEDA56DBE84C8841AFF2BEF82489" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_47C4BAAE1DD352A07344AFF2BEF875FE" xlink:to="loc_srt_MinimumMember_E929CEDA56DBE84C8841AFF2BEF82489" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_566DA4594FD21B595CEFAFF2BEF84E4B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_47C4BAAE1DD352A07344AFF2BEF875FE" xlink:to="loc_srt_MaximumMember_566DA4594FD21B595CEFAFF2BEF84E4B" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_LossContingencyPendingCasesNumber" xlink:label="loc_trs_LossContingencyPendingCasesNumber_46EC18A1B575B6BC2018AFF2BEF8918D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_trs_LossContingencyPendingCasesNumber_46EC18A1B575B6BC2018AFF2BEF8918D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyPendingClaimsNumber" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_E00A8198362023314B57AFF2BEF81772" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_E00A8198362023314B57AFF2BEF81772" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_4EB12C27182D84EF55F7AFF2BEF832AF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_4EB12C27182D84EF55F7AFF2BEF832AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationSettlementExpense" xlink:label="loc_us-gaap_LitigationSettlementExpense_EBB33D2A0EF0E970EBBCAFF2BEF8B5B9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_us-gaap_LitigationSettlementExpense_EBB33D2A0EF0E970EBBCAFF2BEF8B5B9" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance" xlink:label="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_788862EECDC61890EBEAAFF2BEF8B247" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_788862EECDC61890EBEAAFF2BEF8B247" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_EstimatedTimeuntilPrimaryInsuranceisExhausted" xlink:label="loc_trs_EstimatedTimeuntilPrimaryInsuranceisExhausted_05FDEBAACF50F117724EAFF2BEF81EEC" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C077DE6547ADF2FAC50DAFF2BEF8302C" xlink:to="loc_trs_EstimatedTimeuntilPrimaryInsuranceisExhausted_05FDEBAACF50F117724EAFF2BEF81EEC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingenciesCommitmentsAndContingenciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingenciesMetaldyneDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_FF4C91FC751BD6F9817DAFF2BFA4FE9B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_8AE70D9F72EC31E2AD23AFF2BFA495A7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_FF4C91FC751BD6F9817DAFF2BFA4FE9B" xlink:to="loc_us-gaap_LossContingenciesTable_8AE70D9F72EC31E2AD23AFF2BFA495A7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_A2153CBB744F573275F6AFF2BFA4EAFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_8AE70D9F72EC31E2AD23AFF2BFA495A7" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_A2153CBB744F573275F6AFF2BFA4EAFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_C8C4AB658F4350F65BD0AFF2BFA41CF2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_A2153CBB744F573275F6AFF2BFA4EAFA" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_C8C4AB658F4350F65BD0AFF2BFA41CF2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_C8C4AB658F4350F65BD0AFF2BFA41CF2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_A2153CBB744F573275F6AFF2BFA4EAFA" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_C8C4AB658F4350F65BD0AFF2BFA41CF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_1A6E0ED7EB389FA478D8AFF2BFA4F4BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_C8C4AB658F4350F65BD0AFF2BFA41CF2" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_1A6E0ED7EB389FA478D8AFF2BFA4F4BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_8E1E64147BFFEFE6202BAFF2BFA41187" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_8AE70D9F72EC31E2AD23AFF2BFA495A7" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_8E1E64147BFFEFE6202BAFF2BFA41187" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_C533E78BC4C3436092CFAFF2BFA4FFB8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_8E1E64147BFFEFE6202BAFF2BFA41187" xlink:to="loc_us-gaap_LossContingencyNatureDomain_C533E78BC4C3436092CFAFF2BFA4FFB8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_C533E78BC4C3436092CFAFF2BFA4FFB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_8E1E64147BFFEFE6202BAFF2BFA41187" xlink:to="loc_us-gaap_LossContingencyNatureDomain_C533E78BC4C3436092CFAFF2BFA4FFB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_09C5424B20C9B7D30AD4AFF2BFA4803D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_FF4C91FC751BD6F9817DAFF2BFA4FE9B" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_09C5424B20C9B7D30AD4AFF2BFA4803D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsAndContingenciesOrdinaryCourseClaimsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_8449813A31F039B88214AFF2C147148B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_5AE952C689898C2FC55EAFF2C147F3EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_8449813A31F039B88214AFF2C147148B" xlink:to="loc_us-gaap_LossContingenciesTable_5AE952C689898C2FC55EAFF2C147F3EB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseAxis" xlink:label="loc_srt_LitigationCaseAxis_23BF28E0C4B5E4533372AFF2C147824F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_5AE952C689898C2FC55EAFF2C147F3EB" xlink:to="loc_srt_LitigationCaseAxis_23BF28E0C4B5E4533372AFF2C147824F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_3E3AD2A89D51EFF7D528AFF2C1471890_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_23BF28E0C4B5E4533372AFF2C147824F" xlink:to="loc_srt_LitigationCaseTypeDomain_3E3AD2A89D51EFF7D528AFF2C1471890_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_3E3AD2A89D51EFF7D528AFF2C1471890" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_23BF28E0C4B5E4533372AFF2C147824F" xlink:to="loc_srt_LitigationCaseTypeDomain_3E3AD2A89D51EFF7D528AFF2C1471890" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_9A9560BC4C15D2DCB0F6AFF2C147D29F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_5AE952C689898C2FC55EAFF2C147F3EB" xlink:to="loc_us-gaap_LitigationStatusAxis_9A9560BC4C15D2DCB0F6AFF2C147D29F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_2FC117CEC2B2AAEC3671AFF2C1474B6D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_9A9560BC4C15D2DCB0F6AFF2C147D29F" xlink:to="loc_us-gaap_LitigationStatusDomain_2FC117CEC2B2AAEC3671AFF2C1474B6D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_2FC117CEC2B2AAEC3671AFF2C1474B6D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_9A9560BC4C15D2DCB0F6AFF2C147D29F" xlink:to="loc_us-gaap_LitigationStatusDomain_2FC117CEC2B2AAEC3671AFF2C1474B6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_316C9B47AD87C4AE7B76AFF2C14700CE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_5AE952C689898C2FC55EAFF2C147F3EB" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_316C9B47AD87C4AE7B76AFF2C14700CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_04EE0C17D11D08BE73C7AFF2C14706C6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_316C9B47AD87C4AE7B76AFF2C14700CE" xlink:to="loc_us-gaap_LossContingencyNatureDomain_04EE0C17D11D08BE73C7AFF2C14706C6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_04EE0C17D11D08BE73C7AFF2C14706C6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_316C9B47AD87C4AE7B76AFF2C14700CE" xlink:to="loc_us-gaap_LossContingencyNatureDomain_04EE0C17D11D08BE73C7AFF2C14706C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyDamagesAwardedValue" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_3EE131BE20C24525A965AFF2C14787D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_8449813A31F039B88214AFF2C147148B" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_3EE131BE20C24525A965AFF2C14787D0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedBalanceSheetParentheticals" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_38B047C188DD7BFC7789AFF2C004C990" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_338642897BFD34BFDEF0AFF2C004078D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_38B047C188DD7BFC7789AFF2C004C990" xlink:to="loc_us-gaap_StatementTable_338642897BFD34BFDEF0AFF2C004078D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_E4094342F6AC37722529AFF2C0046AB1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_338642897BFD34BFDEF0AFF2C004078D" xlink:to="loc_us-gaap_StatementScenarioAxis_E4094342F6AC37722529AFF2C0046AB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_30AC4BA3D1E65DC304E8AFF2C0044414_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_E4094342F6AC37722529AFF2C0046AB1" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_30AC4BA3D1E65DC304E8AFF2C0044414_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_30AC4BA3D1E65DC304E8AFF2C0044414" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_E4094342F6AC37722529AFF2C0046AB1" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_30AC4BA3D1E65DC304E8AFF2C0044414" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_BDF6372BC76D9BF0E0BAAFF2C00419C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_38B047C188DD7BFC7789AFF2C004C990" xlink:to="loc_us-gaap_AssetsCurrentAbstract_BDF6372BC76D9BF0E0BAAFF2C00419C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_0C8C7FB3A276D90419C2AFF2C004A668" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_BDF6372BC76D9BF0E0BAAFF2C00419C0" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_0C8C7FB3A276D90419C2AFF2C004A668" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_38B047C188DD7BFC7789AFF2C004C990" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_26FA0ED21608657DCF1BAFF2C0041438" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_26FA0ED21608657DCF1BAFF2C0041438" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_9885DD65A7FB7BC12E16AFF2C0041761" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_9885DD65A7FB7BC12E16AFF2C0041761" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_1391A705CE42DE0D3F79AFF2C0048615" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_PreferredStockSharesIssued_1391A705CE42DE0D3F79AFF2C0048615" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_D63B306D224C5907D335AFF2C0044899" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_D63B306D224C5907D335AFF2C0044899" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_923720D54799EB736E5AAFF2C0044ECB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_923720D54799EB736E5AAFF2C0044ECB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_4D3EA8029712F8E66206AFF2C0046148" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_4D3EA8029712F8E66206AFF2C0046148" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_9911BF5D791F6685CC57AFF2C004652A" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_CommonStockSharesIssued_9911BF5D791F6685CC57AFF2C004652A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_31FC1F5ED3EAABB78746AFF2C0046FB7" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_B356E1E0FEC1BB1F2BB6AFF2C0044D41" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_31FC1F5ED3EAABB78746AFF2C0046FB7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedBalanceSheetStatement" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_2A54B25E8FAC6B1DB793B06C712BE3A5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_48F67F17755DCD737778B06C71294B3B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2A54B25E8FAC6B1DB793B06C712BE3A5" xlink:to="loc_us-gaap_StatementTable_48F67F17755DCD737778B06C71294B3B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_F3C4EBA48DA09935BCD3B06C712A21D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_48F67F17755DCD737778B06C71294B3B" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_F3C4EBA48DA09935BCD3B06C712A21D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_410F7AA3EC4E98DCCD4AB06C712AB3A8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_F3C4EBA48DA09935BCD3B06C712A21D8" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_410F7AA3EC4E98DCCD4AB06C712AB3A8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_410F7AA3EC4E98DCCD4AB06C712AB3A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_F3C4EBA48DA09935BCD3B06C712A21D8" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_410F7AA3EC4E98DCCD4AB06C712AB3A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2A54B25E8FAC6B1DB793B06C712BE3A5" xlink:to="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_9B5932D59FECF7005B71B06C712D9AAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_9B5932D59FECF7005B71B06C712D9AAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_2DC50DD06B46657397FBB06C712D4E2F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_2DC50DD06B46657397FBB06C712D4E2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_844A2FFB872DA1F8E036B06C712E74F8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:to="loc_us-gaap_InventoryNet_844A2FFB872DA1F8E036B06C712E74F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_913EDACF1BBF0ED050AFB06C712E84FA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_913EDACF1BBF0ED050AFB06C712E84FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_48110D7EC5C350A7B69AB06C712E080F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_E8E56DDC3960F8B57C59B06C712D65ED" xlink:to="loc_us-gaap_AssetsCurrent_48110D7EC5C350A7B69AB06C712E080F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_5B12D169CBEBCB587D28B06C712EB445" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_5B12D169CBEBCB587D28B06C712EB445" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_128CAAC2895854186E04B06C712EB104" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_Goodwill_128CAAC2895854186E04B06C712EB104" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_867E00C7FE29FDC34BE7B06C712F6A27" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_867E00C7FE29FDC34BE7B06C712F6A27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent_861D3AC57ECBE70D8F91B06C7130AD4A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent_861D3AC57ECBE70D8F91B06C7130AD4A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_F700F7967A90F3B682C8B06C7130946A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_F700F7967A90F3B682C8B06C7130946A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_A8F37D54287FF1DE4308B06C7130C1EE" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_25C91C8C38A62D77ADE5B06C712BAA20" xlink:to="loc_us-gaap_Assets_A8F37D54287FF1DE4308B06C7130C1EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2A54B25E8FAC6B1DB793B06C712BE3A5" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_D922AFA64D03C05D18DDB06C7130E23D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_D922AFA64D03C05D18DDB06C7130E23D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_57E05EF156E1F3299E75B06C7131B090" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_D922AFA64D03C05D18DDB06C7130E23D" xlink:to="loc_us-gaap_AccountsPayableCurrent_57E05EF156E1F3299E75B06C7131B090" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_72E1C6DFCD56A6F06776B06C71316AF2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_D922AFA64D03C05D18DDB06C7130E23D" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_72E1C6DFCD56A6F06776B06C71316AF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_43781C3C40B4876910DEB06C71329D06" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_D922AFA64D03C05D18DDB06C7130E23D" xlink:to="loc_us-gaap_LiabilitiesCurrent_43781C3C40B4876910DEB06C71329D06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_BCA2243BBB0DA0CFE12BB06C7132A515" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_BCA2243BBB0DA0CFE12BB06C7132A515" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_EC742D3AC13D9BBB7E4FB06C71322689" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_EC742D3AC13D9BBB7E4FB06C71322689" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_0E219E87589D884CABC6B06C71339C82" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_0E219E87589D884CABC6B06C71339C82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_E113C8361321CDB06BF9B06C7133DBE0" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_Liabilities_E113C8361321CDB06BF9B06C7133DBE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_40D45F548A5631E00EBFB06C7133202D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_PreferredStockValue_40D45F548A5631E00EBFB06C7133202D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_08CB824C0699253A6F0AB06C7133BE19" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_CommonStockValue_08CB824C0699253A6F0AB06C7133BE19" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_055031DCF23E23970FE9B06C713317DC" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_055031DCF23E23970FE9B06C713317DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_BBA8DF2F55183B3406CBB06C7133F851" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_BBA8DF2F55183B3406CBB06C7133F851" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_42ABDE47B8B69CE71DD7B06C7135BAE2" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_42ABDE47B8B69CE71DD7B06C7135BAE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_F722DDB7B56D65D9CF80B06C7135EBBA" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_StockholdersEquity_F722DDB7B56D65D9CF80B06C7135EBBA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_B521B58CBF5ED09225BCB06C7135B17A" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_FE8DEC3D143991898C29B06C7130932A" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_B521B58CBF5ED09225BCB06C7135B17A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementOfCashFlowsStatement" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_619AF3F1B10038CD56C9B0FEF053EB45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_StatementTable_619AF3F1B10038CD56C9B0FEF053EB45" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_73932E30B8E39D45F362B0FEF053150D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_619AF3F1B10038CD56C9B0FEF053EB45" xlink:to="loc_us-gaap_StatementScenarioAxis_73932E30B8E39D45F362B0FEF053150D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_607D19A6E242F3E33B18B0FEF0534BF1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_73932E30B8E39D45F362B0FEF053150D" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_607D19A6E242F3E33B18B0FEF0534BF1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_607D19A6E242F3E33B18B0FEF0534BF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_73932E30B8E39D45F362B0FEF053150D" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_607D19A6E242F3E33B18B0FEF0534BF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_90A70373BBBDD1F85B8EB0FEF05360EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_90A70373BBBDD1F85B8EB0FEF05360EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_5A778DA727E4FE7D1832B0FEF053A83D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_90A70373BBBDD1F85B8EB0FEF05360EF" xlink:to="loc_us-gaap_ProfitLoss_5A778DA727E4FE7D1832B0FEF053A83D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_90A70373BBBDD1F85B8EB0FEF05360EF" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets1" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_BA1BDD7484C5076C1ADBB0FEF05317AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_BA1BDD7484C5076C1ADBB0FEF05317AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_A2F5B4FD18FBB244DE5FB0FEF0536FC0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_Depreciation_A2F5B4FD18FBB244DE5FB0FEF0536FC0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_E053C13885DF628845EAB0FEF0533174" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_E053C13885DF628845EAB0FEF0533174" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_8A55D601F2B025A04866B0FEF053753D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_8A55D601F2B025A04866B0FEF053753D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_932EEBA74F908A18110EB0FEF0538856" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_932EEBA74F908A18110EB0FEF0538856" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_DFB4B351D86610C3222EB0FEF053AA85" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_ShareBasedCompensation_DFB4B351D86610C3222EB0FEF053AA85" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_85EBC6260A2432A4FF4FB0FEF0531F80" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_85EBC6260A2432A4FF4FB0FEF0531F80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInReceivables" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivables_DDCD337C263A2F7DC458B0FEF05341D4" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivables_DDCD337C263A2F7DC458B0FEF05341D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_C6BF93EAF1DB067D9CE0B0FEF05360D8" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_C6BF93EAF1DB067D9CE0B0FEF05360D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_E52FCCE0E71F4769A340B0FEF062C2E9" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_E52FCCE0E71F4769A340B0FEF062C2E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_288C8D6B043D05155022B0FEF062AD3E" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_288C8D6B043D05155022B0FEF062AD3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_5C6EA6C86703BB86CB86B0FEF0627400" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_DD46E918B2DA44A55D8BB0FEF053DE2D" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_5C6EA6C86703BB86CB86B0FEF0627400" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_BCE80ADCB5C22236436CB0FEF06207D9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_90A70373BBBDD1F85B8EB0FEF05360EF" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_BCE80ADCB5C22236436CB0FEF06207D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_3F60B82CB0B30C0B0CE3B0FEF062271E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_3F60B82CB0B30C0B0CE3B0FEF062271E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_2AC9D19574F0B630A6F2B0FEF062F5F7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_3F60B82CB0B30C0B0CE3B0FEF062271E" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_2AC9D19574F0B630A6F2B0FEF062F5F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_559913454AD2B49021E3B0FEF062E640" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_3F60B82CB0B30C0B0CE3B0FEF062271E" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_559913454AD2B49021E3B0FEF062E640" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_D35F9096AA76B00018E8B0FEF062CD98" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_3F60B82CB0B30C0B0CE3B0FEF062271E" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_D35F9096AA76B00018E8B0FEF062CD98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_007AE2D3E732F8FB16EBB0FEF06258E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_007AE2D3E732F8FB16EBB0FEF06258E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_03403C3239F1BDC712EFB0FEF06284BF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_03403C3239F1BDC712EFB0FEF06284BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_A79F22FB46D5CDF5419BB0FEF0627196" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_A79F22FB46D5CDF5419BB0FEF0627196" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_FC8DF0B74B1857AD6F81B0FEF0627B97" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_FC8DF0B74B1857AD6F81B0FEF0627B97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_0BFEEF38E7A19C4DDC59B0FEF062CF4E" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_0BFEEF38E7A19C4DDC59B0FEF062CF4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_44CD88A17184AB1108C8B0FEF0627FDA" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_44CD88A17184AB1108C8B0FEF0627FDA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_D9A67067ADA4E3B93853B0FEF062C431" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_D9A67067ADA4E3B93853B0FEF062C431" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_1BFE28303C0FDD5B59ECB0FEF0629C45" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_1BFE28303C0FDD5B59ECB0FEF0629C45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_863E577BDA21DD923A5BB0FEF0626095" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_C05430763A1CF201E016B0FEF0620A2B" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_863E577BDA21DD923A5BB0FEF0626095" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_6FB1523497E046B3DC3FB0FEF062D1D3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_6FB1523497E046B3DC3FB0FEF062D1D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_75DEE036CE977292B787B0FEF06267AE" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_75DEE036CE977292B787B0FEF06267AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_1611410E049419CE53D4B0FEF0626F87" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4B8A0D43A7B46ED7E692B0FEF0539625" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_1611410E049419CE53D4B0FEF0626F87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestPaidNet" xlink:label="loc_us-gaap_InterestPaidNet_97E9C11F8A2F86392975B0FEF0621F66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_1611410E049419CE53D4B0FEF0626F87" xlink:to="loc_us-gaap_InterestPaidNet_97E9C11F8A2F86392975B0FEF0621F66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxesPaid" xlink:label="loc_us-gaap_IncomeTaxesPaid_1E66F928CFC7ADEAA344B0FEF0620633" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_1611410E049419CE53D4B0FEF0626F87" xlink:to="loc_us-gaap_IncomeTaxesPaid_1E66F928CFC7ADEAA344B0FEF0620633" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementOfComprehensiveIncome" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementOfIncomeStatement" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1B521E8BA00242707006B06CE2962661" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_StatementTable_1B521E8BA00242707006B06CE2962661" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_B83B62A15A058D5CECF9B06CE2976C8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1B521E8BA00242707006B06CE2962661" xlink:to="loc_us-gaap_StatementScenarioAxis_B83B62A15A058D5CECF9B06CE2976C8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_191CA449FBA1FBF56A3EB06CE298E685_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_B83B62A15A058D5CECF9B06CE2976C8C" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_191CA449FBA1FBF56A3EB06CE298E685_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_191CA449FBA1FBF56A3EB06CE298E685" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_B83B62A15A058D5CECF9B06CE2976C8C" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_191CA449FBA1FBF56A3EB06CE298E685" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_B4DB6D0B44D503E33291B06CE2981A96" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_Revenues_B4DB6D0B44D503E33291B06CE2981A96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_7CD59B1E1994DAC88CABB06CE298A6FB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_7CD59B1E1994DAC88CABB06CE298A6FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_2BE82BA522161644E720B06CE298DD1A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_GrossProfit_2BE82BA522161644E720B06CE298DD1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_73B641B21C70D447F508B06CE29989A9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_73B641B21C70D447F508B06CE29989A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_B33EF3E7245AB9F425C8B06CE299544F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_OperatingIncomeLoss_B33EF3E7245AB9F425C8B06CE299544F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_F429D1F9447D0DC6D79BB06CE29A5AE2" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_F429D1F9447D0DC6D79BB06CE29A5AE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_4FEDBF365824048F6414B06CE29AF934" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_F429D1F9447D0DC6D79BB06CE29A5AE2" xlink:to="loc_us-gaap_InterestExpense_4FEDBF365824048F6414B06CE29AF934" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_A9734055C66F6AE05EFAB06CE29A9EDC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_F429D1F9447D0DC6D79BB06CE29A5AE2" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_A9734055C66F6AE05EFAB06CE29A9EDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_4109E7BBA94B0EB24495B06CE29AF595" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_F429D1F9447D0DC6D79BB06CE29A5AE2" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_4109E7BBA94B0EB24495B06CE29AF595" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_2280E73F6A13389D2E74B06CE29BC6A8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_F429D1F9447D0DC6D79BB06CE29A5AE2" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_2280E73F6A13389D2E74B06CE29BC6A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_E5127E626E2253CE745AB06CE29BE871" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_E5127E626E2253CE745AB06CE29BE871" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_F83BDD84B6CAFE049FCCB06CE29B1969" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_F83BDD84B6CAFE049FCCB06CE29B1969" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_D2ACEB0EF43170D6DFCFB06CE29B48B2" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_NetIncomeLoss_D2ACEB0EF43170D6DFCFB06CE29B48B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_94085CF194A04C3739DBB06CE29CAA5F" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_94085CF194A04C3739DBB06CE29CAA5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_A5B91CC3064824537D29B06CE29CCE76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_94085CF194A04C3739DBB06CE29CAA5F" xlink:to="loc_us-gaap_EarningsPerShareBasic_A5B91CC3064824537D29B06CE29CCE76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_47305F883EBF3802C8E2B06CE29C7D61" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_94085CF194A04C3739DBB06CE29CAA5F" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_47305F883EBF3802C8E2B06CE29C7D61" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDilutedAbstract" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_FEDBBF562F1F57AFA3E2B06CE29D24EE" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8F6724205B809CF116F3B06CE29892E5" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_FEDBBF562F1F57AFA3E2B06CE29D24EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_451AD39D3966CDA7A0C6B06CE29D295D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_FEDBBF562F1F57AFA3E2B06CE29D24EE" xlink:to="loc_us-gaap_EarningsPerShareDiluted_451AD39D3966CDA7A0C6B06CE29D295D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_9095D1A1B7EDB69E675BB06CE29D6DF0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_FEDBBF562F1F57AFA3E2B06CE29D24EE" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_9095D1A1B7EDB69E675BB06CE29D6DF0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementOfShareholdersEquityStatement" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_84BB88A5A36978561989A7BE308E461C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_StatementTable_84BB88A5A36978561989A7BE308E461C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_FCFD68AABF174EBDAAFAA7BE308E6A05" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_84BB88A5A36978561989A7BE308E461C" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_FCFD68AABF174EBDAAFAA7BE308E6A05" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_FCFD68AABF174EBDAAFAA7BE308E6A05" xlink:to="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_FCFD68AABF174EBDAAFAA7BE308E6A05" xlink:to="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_907539E5AAD3EA5C6BC2A7BE308F640B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729" xlink:to="loc_us-gaap_CommonStockMember_907539E5AAD3EA5C6BC2A7BE308F640B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_2B199F606B791C04CD9DA7BE30909AE1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_2B199F606B791C04CD9DA7BE30909AE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_7457E0DE18C1070D6C2EA7BE30909380" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729" xlink:to="loc_us-gaap_RetainedEarningsMember_7457E0DE18C1070D6C2EA7BE30909380" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1304DD258B01CAEE9B94A7BE30909CB2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5A2666C0AAA477DBF625A7BE308F5729" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1304DD258B01CAEE9B94A7BE30909CB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_CF086961206D8B01E77DA7BE3091ABFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_CF086961206D8B01E77DA7BE3091ABFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_E247D0C1076F9CDE0259A7BE3091D7F5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_NetIncomeLoss_E247D0C1076F9CDE0259A7BE3091D7F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_BFB46D9C77D742DEE4E9A7BE309210F5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_BFB46D9C77D742DEE4E9A7BE309210F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_710CF8B54BE2620A96EAA7BE3092A1FF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_710CF8B54BE2620A96EAA7BE3092A1FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_87BD4ED4AF814C56B32BA7BE30920A29" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_87BD4ED4AF814C56B32BA7BE30920A29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_28ED275BB77AB8A892DDA7BE3092370E" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_E4EEF7A49483B3283DEFA7BE309165D9" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_28ED275BB77AB8A892DDA7BE3092370E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlans" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_67BF927248DFAFD7E91E9D32FCA8E2A5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ECB6A97088AC5F755B349D32FCA7DC2C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_67BF927248DFAFD7E91E9D32FCA8E2A5" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ECB6A97088AC5F755B349D32FCA7DC2C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_857720B6023BDEDABD0B9D32FCA877FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ECB6A97088AC5F755B349D32FCA7DC2C" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_857720B6023BDEDABD0B9D32FCA877FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_B53904BEF8F9BE88EF4E9D32FCA81AE9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_857720B6023BDEDABD0B9D32FCA877FB" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_B53904BEF8F9BE88EF4E9D32FCA81AE9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_B53904BEF8F9BE88EF4E9D32FCA81AE9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_857720B6023BDEDABD0B9D32FCA877FB" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_B53904BEF8F9BE88EF4E9D32FCA81AE9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_D9919C81DDF93DDE5EE99D32FCA89555" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_B53904BEF8F9BE88EF4E9D32FCA81AE9" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_D9919C81DDF93DDE5EE99D32FCA89555" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_FC3D7A06CF223E46EB2C9D32FCA9DF95" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_67BF927248DFAFD7E91E9D32FCA8E2A5" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_FC3D7A06CF223E46EB2C9D32FCA9DF95" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_9E5DE8E9A8C9A71ACE2C9D32FCA91F73" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_67BF927248DFAFD7E91E9D32FCA8E2A5" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_9E5DE8E9A8C9A71ACE2C9D32FCA91F73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_17830EE9702EFB99E0389D32FCA991C0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_67BF927248DFAFD7E91E9D32FCA8E2A5" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_17830EE9702EFB99E0389D32FCA991C0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_0543E92D301B8515D7159D333E39B3EE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_0543E92D301B8515D7159D333E39B3EE" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_FD6079F157FDAF1EFA799D333E3A5B84" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_0543E92D301B8515D7159D333E39B3EE" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_FD6079F157FDAF1EFA799D333E3A5B84" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_9ED53A511F268A139AD19D333E3A775E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_FD6079F157FDAF1EFA799D333E3A5B84" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_9ED53A511F268A139AD19D333E3A775E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_9ED53A511F268A139AD19D333E3A775E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_FD6079F157FDAF1EFA799D333E3A5B84" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_9ED53A511F268A139AD19D333E3A775E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_F4562B862ED7827405009D333E3A7F70" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_9ED53A511F268A139AD19D333E3A775E" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_F4562B862ED7827405009D333E3A7F70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_FFFF7C90E1219E118A689D333E3BE9C6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_9ED53A511F268A139AD19D333E3A775E" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_FFFF7C90E1219E118A689D333E3BE9C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_3861ED1D3D39CCD9DBDB9D333E3B0FF7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_3861ED1D3D39CCD9DBDB9D333E3B0FF7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_2C3DD4FC2AC9747F38259D333E3B0D5B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_2C3DD4FC2AC9747F38259D333E3B0D5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_9865BC8E194A8EB8036F9D333E3C39A0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_9865BC8E194A8EB8036F9D333E3C39A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_6DB5A5A353B00CDD159D9D333E3C745F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_6DB5A5A353B00CDD159D9D333E3C745F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_3ABFAE8F90186E14A9BB9D333E3CB945" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_3ABFAE8F90186E14A9BB9D333E3CB945" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_3C6FB51513778346C3C79D333E3C1B0D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_3C6FB51513778346C3C79D333E3C1B0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_0448DEAF06447AE078189D333E3D19AE" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_AFB40A21DB55B56D27CF9D333E3B6977" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_0448DEAF06447AE078189D333E3D19AE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstruments" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativeNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_069943B966D9B1F44EC8F77F47470CD8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:to="loc_us-gaap_HedgingDesignationAxis_069943B966D9B1F44EC8F77F47470CD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_C690233F44FF9D4A39BAF77F474746F9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_069943B966D9B1F44EC8F77F47470CD8" xlink:to="loc_us-gaap_HedgingDesignationDomain_C690233F44FF9D4A39BAF77F474746F9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_C690233F44FF9D4A39BAF77F474746F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_069943B966D9B1F44EC8F77F47470CD8" xlink:to="loc_us-gaap_HedgingDesignationDomain_C690233F44FF9D4A39BAF77F474746F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_3FEEABA212F27E589D7FF77F4748C9F2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_C690233F44FF9D4A39BAF77F474746F9" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_3FEEABA212F27E589D7FF77F4748C9F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_6CD9C625261C45B5F497F77F47490EC5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:to="loc_srt_RangeAxis_6CD9C625261C45B5F497F77F47490EC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_484E944EDF025E8378DAF77F4749497D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6CD9C625261C45B5F497F77F47490EC5" xlink:to="loc_srt_RangeMember_484E944EDF025E8378DAF77F4749497D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_484E944EDF025E8378DAF77F4749497D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6CD9C625261C45B5F497F77F47490EC5" xlink:to="loc_srt_RangeMember_484E944EDF025E8378DAF77F4749497D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_E64BDDF621115C42ABADF77F474919A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_484E944EDF025E8378DAF77F4749497D" xlink:to="loc_srt_MaximumMember_E64BDDF621115C42ABADF77F474919A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_1FAE06410A2E8E02F482F77F474A2A20" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_484E944EDF025E8378DAF77F4749497D" xlink:to="loc_srt_MinimumMember_1FAE06410A2E8E02F482F77F474A2A20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_07A380066B8DD6261FF1F77F474AA565" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:to="loc_us-gaap_DebtInstrumentAxis_07A380066B8DD6261FF1F77F474AA565" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_240C3785D181210FC9C4F77F474B238B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_07A380066B8DD6261FF1F77F474AA565" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_240C3785D181210FC9C4F77F474B238B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_240C3785D181210FC9C4F77F474B238B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_07A380066B8DD6261FF1F77F474AA565" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_240C3785D181210FC9C4F77F474B238B" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SeniorSecuredTermLoanMember" xlink:label="loc_trs_SeniorSecuredTermLoanMember_BBCB6C1D3A09E93E666FF77F474B8004" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_240C3785D181210FC9C4F77F474B238B" xlink:to="loc_trs_SeniorSecuredTermLoanMember_BBCB6C1D3A09E93E666FF77F474B8004" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_6217FA39C9C8DE9E899FF77F474B76CA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_6217FA39C9C8DE9E899FF77F474B76CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_6217FA39C9C8DE9E899FF77F474B76CA" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_6217FA39C9C8DE9E899FF77F474B76CA" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_9B7AC6455A8285D1FF2EF77F474C349D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_9B7AC6455A8285D1FF2EF77F474C349D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_9AB60C775E4F5D62A95CF77F474C5116" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE" xlink:to="loc_us-gaap_ForeignExchangeContractMember_9AB60C775E4F5D62A95CF77F474C5116" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_F5DD969709C2EB0345C8F77F474C661B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_66D42EC744DCB76F06ECF77F474B97FE" xlink:to="loc_us-gaap_InterestRateSwapMember_F5DD969709C2EB0345C8F77F474C661B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_BC078FAE53AC9B52A0CEF77F474CE678" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_BC078FAE53AC9B52A0CEF77F474CE678" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_D5BE840ED017991B659CF77F474D5F5E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_BC078FAE53AC9B52A0CEF77F474CE678" xlink:to="loc_us-gaap_HedgingRelationshipDomain_D5BE840ED017991B659CF77F474D5F5E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_D5BE840ED017991B659CF77F474D5F5E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_BC078FAE53AC9B52A0CEF77F474CE678" xlink:to="loc_us-gaap_HedgingRelationshipDomain_D5BE840ED017991B659CF77F474D5F5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetInvestmentHedgingMember" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_9C2718017752D28F39F1F77F474D05FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_D5BE840ED017991B659CF77F474D5F5E" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_9C2718017752D28F39F1F77F474D05FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_652AF2D2C42D4BA31B29F77F474E7C0A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_D5BE840ED017991B659CF77F474D5F5E" xlink:to="loc_us-gaap_CashFlowHedgingMember_652AF2D2C42D4BA31B29F77F474E7C0A" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DerivativeMaturityDateAxis" xlink:label="loc_trs_DerivativeMaturityDateAxis_0672ECAF0728313676E5F77F474E0C81" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3714BFC27C6EC258FD51F77F4746A654" xlink:to="loc_trs_DerivativeMaturityDateAxis_0672ECAF0728313676E5F77F474E0C81" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DerivativeMaturityDateDomain" xlink:label="loc_trs_DerivativeMaturityDateDomain_1C45E0F4D3233AB937B9F77F474E38A9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DerivativeMaturityDateAxis_0672ECAF0728313676E5F77F474E0C81" xlink:to="loc_trs_DerivativeMaturityDateDomain_1C45E0F4D3233AB937B9F77F474E38A9_default" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DerivativeMaturityDateDomain" xlink:label="loc_trs_DerivativeMaturityDateDomain_1C45E0F4D3233AB937B9F77F474E38A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DerivativeMaturityDateAxis_0672ECAF0728313676E5F77F474E0C81" xlink:to="loc_trs_DerivativeMaturityDateDomain_1C45E0F4D3233AB937B9F77F474E38A9" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DerivativeJune2020MaturityMember" xlink:label="loc_trs_DerivativeJune2020MaturityMember_EF7F17F45387BCF41344F77F474E3A12" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_1C45E0F4D3233AB937B9F77F474E38A9" xlink:to="loc_trs_DerivativeJune2020MaturityMember_EF7F17F45387BCF41344F77F474E3A12" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_C0E9D3B161783B8B4527F77F474F2AC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_C0E9D3B161783B8B4527F77F474F2AC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1" xlink:label="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_337BFC47B5E3872DB198F77F474FFB16" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_337BFC47B5E3872DB198F77F474FFB16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_E9C929764ED80B65E785F77F474F5365" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_invest_DerivativeNotionalAmount_E9C929764ED80B65E785F77F474F5365" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFixedInterestRate" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_47252C5E398E8906ACDEF77F475019FC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_47252C5E398E8906ACDEF77F475019FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeMaturityDates" xlink:label="loc_us-gaap_DerivativeMaturityDates_9C68C7F9E1AC0C707D3CF77F47506CCD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_DerivativeMaturityDates_9C68C7F9E1AC0C707D3CF77F47506CCD" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Cashpaidatterminationofinterestrateswap" xlink:label="loc_trs_Cashpaidatterminationofinterestrateswap_0623C1E231DF98AAE635F77F4750FB82" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_trs_Cashpaidatterminationofinterestrateswap_0623C1E231DF98AAE635F77F4750FB82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_34DD5A5FA0740EC4608DF77F4750593C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_34DD5A5FA0740EC4608DF77F4750593C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax_BC4A0D85A7DE1410702FF77F47505EF5" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_D9F28B887F2E7B27BD62F77F474FEDC2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax_BC4A0D85A7DE1410702FF77F47505EF5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedAsHedgingFinancialPerformanceDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_9909C564EA5ADB96BBF6AFF2C07CB458" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_9909C564EA5ADB96BBF6AFF2C07CB458" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_EB4818D65C7A64386A74AFF2C06C6929" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_EB4818D65C7A64386A74AFF2C06C6929" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_7E3BDAF5226B680E2442AFF2C06C35C4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_EB4818D65C7A64386A74AFF2C06C6929" xlink:to="loc_us-gaap_HedgingRelationshipDomain_7E3BDAF5226B680E2442AFF2C06C35C4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_7E3BDAF5226B680E2442AFF2C06C35C4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_EB4818D65C7A64386A74AFF2C06C6929" xlink:to="loc_us-gaap_HedgingRelationshipDomain_7E3BDAF5226B680E2442AFF2C06C35C4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetInvestmentHedgingMember" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_3E239FEE7892EC614291AFF2C06C2B96" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_7E3BDAF5226B680E2442AFF2C06C35C4" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_3E239FEE7892EC614291AFF2C06C2B96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisposalGroupClassificationAxis" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_1D177C1CEFEF4AB43BC5AFF2C06C6642" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_1D177C1CEFEF4AB43BC5AFF2C06C6642" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_38933B46107A501C448CAFF2C06C4C9C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_1D177C1CEFEF4AB43BC5AFF2C06C6642" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_38933B46107A501C448CAFF2C06C4C9C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_38933B46107A501C448CAFF2C06C4C9C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_1D177C1CEFEF4AB43BC5AFF2C06C6642" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_38933B46107A501C448CAFF2C06C4C9C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_E952F1EDF2D6033A7D3EAFF2C06C70E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_38933B46107A501C448CAFF2C06C4C9C" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember_E952F1EDF2D6033A7D3EAFF2C06C70E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_7ABCC3BD9A5D3B0E7E46AFF2C07C997F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:to="loc_us-gaap_HedgingDesignationAxis_7ABCC3BD9A5D3B0E7E46AFF2C07C997F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_64933C2FBCFA2F26F37BAFF2C07C58E9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_7ABCC3BD9A5D3B0E7E46AFF2C07C997F" xlink:to="loc_us-gaap_HedgingDesignationDomain_64933C2FBCFA2F26F37BAFF2C07C58E9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_64933C2FBCFA2F26F37BAFF2C07C58E9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_7ABCC3BD9A5D3B0E7E46AFF2C07C997F" xlink:to="loc_us-gaap_HedgingDesignationDomain_64933C2FBCFA2F26F37BAFF2C07C58E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_0B7494C2899BE5B17D8BAFF2C07CE24D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_64933C2FBCFA2F26F37BAFF2C07C58E9" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_0B7494C2899BE5B17D8BAFF2C07CE24D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_B33CF14B3F6E1A7EC4AEAFF2C07CDE45" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_B33CF14B3F6E1A7EC4AEAFF2C07CDE45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B33CF14B3F6E1A7EC4AEAFF2C07CDE45" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B33CF14B3F6E1A7EC4AEAFF2C07CDE45" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_ECF0FCCF4B8F88A08A97AFF2C07C27A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_ECF0FCCF4B8F88A08A97AFF2C07C27A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_C470C2F744E53F2DD8ADAFF2C07CB212" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650" xlink:to="loc_us-gaap_InterestRateSwapMember_C470C2F744E53F2DD8ADAFF2C07CB212" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_ECF6259C5F389BEDEDA5AFF2C07C4AFE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_9F26C3FD5E5E4483EDB9AFF2C07CF650" xlink:to="loc_us-gaap_ForeignExchangeContractMember_ECF6259C5F389BEDEDA5AFF2C07C4AFE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_808C41106CAC0802B18EAFF2C07CA2EC" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_4989731E682997745166AFF2C06CA661" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_808C41106CAC0802B18EAFF2C07CA2EC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_808C41106CAC0802B18EAFF2C07CA2EC" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_808C41106CAC0802B18EAFF2C07CA2EC" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpenseMember" xlink:label="loc_us-gaap_InterestExpenseMember_C2A7D8CC303098A597C0AFF2C07CFFAA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B" xlink:to="loc_us-gaap_InterestExpenseMember_C2A7D8CC303098A597C0AFF2C07CFFAA" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DebtfinancingandrelatedexpensesMember" xlink:label="loc_trs_DebtfinancingandrelatedexpensesMember_F98FC512666DC92C0107AFF2C07C4A98" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B" xlink:to="loc_trs_DebtfinancingandrelatedexpensesMember_F98FC512666DC92C0107AFF2C07C4A98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_6BCAB3B967CE0C013475AFF2C07C815F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_CE09714722094764AF0EAFF2C07C333B" xlink:to="loc_us-gaap_CostOfSalesMember_6BCAB3B967CE0C013475AFF2C07C815F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax_988918009BA918352BBAAFF2C07C3CFD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_9909C564EA5ADB96BBF6AFF2C07CB458" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax_988918009BA918352BBAAFF2C07C3CFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_2AE83F815CA8946D3FFFAFF2C07CCE5D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_9909C564EA5ADB96BBF6AFF2C07CB458" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_2AE83F815CA8946D3FFFAFF2C07CCE5D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedAsHedgingFinancialPerformanceNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_15552BB279D651778329AFF2C0ABBAFB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_ED479265AF5288F8CF16AFF2C0ABFCD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_15552BB279D651778329AFF2C0ABBAFB" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_ED479265AF5288F8CF16AFF2C0ABFCD4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_3CEBC78FDDB2C3D0E280AFF2C0AB9954" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_ED479265AF5288F8CF16AFF2C0ABFCD4" xlink:to="loc_us-gaap_HedgingDesignationAxis_3CEBC78FDDB2C3D0E280AFF2C0AB9954" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_A5D4F98AC06E84ACFAC9AFF2C0AB2637_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_3CEBC78FDDB2C3D0E280AFF2C0AB9954" xlink:to="loc_us-gaap_HedgingDesignationDomain_A5D4F98AC06E84ACFAC9AFF2C0AB2637_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_A5D4F98AC06E84ACFAC9AFF2C0AB2637" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_3CEBC78FDDB2C3D0E280AFF2C0AB9954" xlink:to="loc_us-gaap_HedgingDesignationDomain_A5D4F98AC06E84ACFAC9AFF2C0AB2637" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_0885FCA1E1AB4987EEB5AFF2C0AB9842" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_A5D4F98AC06E84ACFAC9AFF2C0AB2637" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_0885FCA1E1AB4987EEB5AFF2C0AB9842" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_6BFA60AB5E963CE0C847AFF2C0AB7334" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_ED479265AF5288F8CF16AFF2C0ABFCD4" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_6BFA60AB5E963CE0C847AFF2C0AB7334" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_5AC29C682761B9793D56AFF2C0AB609E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_6BFA60AB5E963CE0C847AFF2C0AB7334" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_5AC29C682761B9793D56AFF2C0AB609E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_5AC29C682761B9793D56AFF2C0AB609E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_6BFA60AB5E963CE0C847AFF2C0AB7334" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_5AC29C682761B9793D56AFF2C0AB609E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpenseMember" xlink:label="loc_us-gaap_InterestExpenseMember_FB06E6B2D211C140D03DAFF2C0AB92BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5AC29C682761B9793D56AFF2C0AB609E" xlink:to="loc_us-gaap_InterestExpenseMember_FB06E6B2D211C140D03DAFF2C0AB92BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_8D9473CF3F786EBAB0B7AFF2C0AB4BFD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_ED479265AF5288F8CF16AFF2C0ABFCD4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_8D9473CF3F786EBAB0B7AFF2C0AB4BFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_94A6E1C2A33DB0E91D6EAFF2C0ABDE1F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8D9473CF3F786EBAB0B7AFF2C0AB4BFD" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_94A6E1C2A33DB0E91D6EAFF2C0ABDE1F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_94A6E1C2A33DB0E91D6EAFF2C0ABDE1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8D9473CF3F786EBAB0B7AFF2C0AB4BFD" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_94A6E1C2A33DB0E91D6EAFF2C0ABDE1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_1F85891DBA17A93ED99BAFF2C0AB1F4D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_94A6E1C2A33DB0E91D6EAFF2C0ABDE1F" xlink:to="loc_us-gaap_InterestRateSwapMember_1F85891DBA17A93ED99BAFF2C0AB1F4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_00ED8DC9ACACE1D26430AFF2C0AB7E26" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_94A6E1C2A33DB0E91D6EAFF2C0ABDE1F" xlink:to="loc_us-gaap_ForeignExchangeContractMember_00ED8DC9ACACE1D26430AFF2C0AB7E26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_CB6842E47173110D4F29AFF2C0AB1F88" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_15552BB279D651778329AFF2C0ABBAFB" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_CB6842E47173110D4F29AFF2C0AB1F88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_4F327E0CA2387B5963EAAFF2C0ABDE02" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_15552BB279D651778329AFF2C0ABBAFB" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_4F327E0CA2387B5963EAAFF2C0ABDE02" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedAsHedgingFinancialPositionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_52761E29A9782F2D5DD3AFF2BEAA1DB0" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_52761E29A9782F2D5DD3AFF2BEAA1DB0" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04EF7C33234F3726A131AFF2BEAA9817" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04EF7C33234F3726A131AFF2BEAA9817" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_A5A06E9AD83C40A4C115AFF2BEAADAC4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04EF7C33234F3726A131AFF2BEAA9817" xlink:to="loc_us-gaap_HedgingRelationshipDomain_A5A06E9AD83C40A4C115AFF2BEAADAC4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_A5A06E9AD83C40A4C115AFF2BEAADAC4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04EF7C33234F3726A131AFF2BEAA9817" xlink:to="loc_us-gaap_HedgingRelationshipDomain_A5A06E9AD83C40A4C115AFF2BEAADAC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetInvestmentHedgingMember" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_2F503190AA5E47143A60AFF2BEAACD33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_A5A06E9AD83C40A4C115AFF2BEAADAC4" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_2F503190AA5E47143A60AFF2BEAACD33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_37C38471DFE84B16FB27AFF2BEAAC05B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_37C38471DFE84B16FB27AFF2BEAAC05B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1E6BA17D5EF58F4562F2AFF2BEAA013A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_37C38471DFE84B16FB27AFF2BEAAC05B" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1E6BA17D5EF58F4562F2AFF2BEAA013A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1E6BA17D5EF58F4562F2AFF2BEAA013A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_37C38471DFE84B16FB27AFF2BEAAC05B" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1E6BA17D5EF58F4562F2AFF2BEAA013A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpenseMember" xlink:label="loc_us-gaap_InterestExpenseMember_C77A9726546770C9F432AFF2BEAAB059" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1E6BA17D5EF58F4562F2AFF2BEAA013A" xlink:to="loc_us-gaap_InterestExpenseMember_C77A9726546770C9F432AFF2BEAAB059" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_38D195C1670E6A4E6BFEAFF2BEAA4593" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_38D195C1670E6A4E6BFEAFF2BEAA4593" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_38D195C1670E6A4E6BFEAFF2BEAA4593" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_38D195C1670E6A4E6BFEAFF2BEAA4593" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_6943A42F73D7B253350FAFF2BEAAA202" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_6943A42F73D7B253350FAFF2BEAAA202" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_FBC5AE4E87F16514E5D6AFF2BEAAE9DB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106" xlink:to="loc_us-gaap_InterestRateSwapMember_FBC5AE4E87F16514E5D6AFF2BEAAE9DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_AE702146C80189E6D64CAFF2BEAA0CB8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5FE5462FBB4E3EA1CCBBAFF2BEAA2106" xlink:to="loc_us-gaap_ForeignExchangeContractMember_AE702146C80189E6D64CAFF2BEAA0CB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_2EB7FD20A1929543AB0CAFF2BEAA1ED3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:to="loc_us-gaap_HedgingDesignationAxis_2EB7FD20A1929543AB0CAFF2BEAA1ED3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_DA9C61B508433EEF6973AFF2BEAA5F92_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_2EB7FD20A1929543AB0CAFF2BEAA1ED3" xlink:to="loc_us-gaap_HedgingDesignationDomain_DA9C61B508433EEF6973AFF2BEAA5F92_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_DA9C61B508433EEF6973AFF2BEAA5F92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_2EB7FD20A1929543AB0CAFF2BEAA1ED3" xlink:to="loc_us-gaap_HedgingDesignationDomain_DA9C61B508433EEF6973AFF2BEAA5F92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_7BA7BC58CF34AD86BF69AFF2BEAA7093" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_DA9C61B508433EEF6973AFF2BEAA5F92" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_7BA7BC58CF34AD86BF69AFF2BEAA7093" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_A585A2FE4C3CDC84BF94AFF2BEAAF920" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_03CF329D6826C81B5CF1AFF2BEAA593B" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_A585A2FE4C3CDC84BF94AFF2BEAAF920" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_A585A2FE4C3CDC84BF94AFF2BEAAF920" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_A585A2FE4C3CDC84BF94AFF2BEAAF920" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsMember" xlink:label="loc_us-gaap_OtherAssetsMember_A2D4F2B2428D0FFF7120AFF2BEAA1B6C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81" xlink:to="loc_us-gaap_OtherAssetsMember_A2D4F2B2428D0FFF7120AFF2BEAA1B6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedLiabilitiesMember" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_AE4F975F60C309AD19C6AFF2BEAA120F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_AE4F975F60C309AD19C6AFF2BEAA120F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesMember" xlink:label="loc_us-gaap_OtherLiabilitiesMember_6C51759CDB8CEF10AB47AFF2BEAA4C97" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_61FC8AC3284624E12AE9AFF2BEAA7D81" xlink:to="loc_us-gaap_OtherLiabilitiesMember_6C51759CDB8CEF10AB47AFF2BEAA4C97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_A35F19139D350A27A84BAFF2BEAA16B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_52761E29A9782F2D5DD3AFF2BEAA1DB0" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_A35F19139D350A27A84BAFF2BEAA16B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_3901D7A3027AC4F1CBACAFF2BEAA5746" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_52761E29A9782F2D5DD3AFF2BEAA1DB0" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_3901D7A3027AC4F1CBACAFF2BEAA5746" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0A27A7A0566607B2CCD8AFF2C185FB0C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_75C068159692EA20035EAFF2C176E76F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0A27A7A0566607B2CCD8AFF2C185FB0C" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_75C068159692EA20035EAFF2C176E76F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_DE84D1A2668823DACD6CAFF2C176E1CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_75C068159692EA20035EAFF2C176E76F" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_DE84D1A2668823DACD6CAFF2C176E1CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_B2F0F3B88813C61353BDAFF2C1767986_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_DE84D1A2668823DACD6CAFF2C176E1CC" xlink:to="loc_us-gaap_HedgingRelationshipDomain_B2F0F3B88813C61353BDAFF2C1767986_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_B2F0F3B88813C61353BDAFF2C1767986" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_DE84D1A2668823DACD6CAFF2C176E1CC" xlink:to="loc_us-gaap_HedgingRelationshipDomain_B2F0F3B88813C61353BDAFF2C1767986" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetInvestmentHedgingMember" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_A218276F3F1A02CEA693AFF2C1767759" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_B2F0F3B88813C61353BDAFF2C1767986" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_A218276F3F1A02CEA693AFF2C1767759" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_FACE330EF219BDC37223AFF2C1762418" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_75C068159692EA20035EAFF2C176E76F" xlink:to="loc_us-gaap_FinancialInstrumentAxis_FACE330EF219BDC37223AFF2C1762418" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_FACE330EF219BDC37223AFF2C1762418" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_FACE330EF219BDC37223AFF2C1762418" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_0B32C481801D591FC028AFF2C176D0D9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_0B32C481801D591FC028AFF2C176D0D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_6B47945795094A8B9B4EAFF2C1763810" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8" xlink:to="loc_us-gaap_InterestRateSwapMember_6B47945795094A8B9B4EAFF2C1763810" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_30D65583D28B6C764ECAAFF2C176A6B1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_460B2D92DAEDC6D85FEAAFF2C17608A8" xlink:to="loc_us-gaap_ForeignExchangeContractMember_30D65583D28B6C764ECAAFF2C176A6B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_807BA76E649EB8C0F6FAAFF2C1765DEA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_75C068159692EA20035EAFF2C176E76F" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_807BA76E649EB8C0F6FAAFF2C1765DEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1CA3472C03D0A6FE8C94AFF2C17670C5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_807BA76E649EB8C0F6FAAFF2C1765DEA" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1CA3472C03D0A6FE8C94AFF2C17670C5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1CA3472C03D0A6FE8C94AFF2C17670C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_807BA76E649EB8C0F6FAAFF2C1765DEA" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1CA3472C03D0A6FE8C94AFF2C17670C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_726483559618C873CCBDAFF2C1856F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_1CA3472C03D0A6FE8C94AFF2C17670C5" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_726483559618C873CCBDAFF2C1856F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01BE7730DB36300C0580AFF2C185E07F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_75C068159692EA20035EAFF2C176E76F" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01BE7730DB36300C0580AFF2C185E07F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01BE7730DB36300C0580AFF2C185E07F" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01BE7730DB36300C0580AFF2C185E07F" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_C6BB714F87DA646BF84EAFF2C185246F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_C6BB714F87DA646BF84EAFF2C185246F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_1A9C7C78F2273EFB4F5DAFF2C1855161" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_1A9C7C78F2273EFB4F5DAFF2C1855161" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_52AF7340026FA7A5BFB5AFF2C1856BD1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D59F8FBF2B5CBE42D580AFF2C185AE47" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_52AF7340026FA7A5BFB5AFF2C1856BD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_80EB8D87964888231495AFF2C1856116" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0A27A7A0566607B2CCD8AFF2C185FB0C" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_80EB8D87964888231495AFF2C1856116" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_us-gaap_DerivativeAssets_37C27A9220262BB35F75AFF2C185B7D2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0A27A7A0566607B2CCD8AFF2C185FB0C" xlink:to="loc_us-gaap_DerivativeAssets_37C27A9220262BB35F75AFF2C185B7D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaap_DerivativeLiabilities_FC39900B1180857D0A04AFF2C185CD06" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0A27A7A0566607B2CCD8AFF2C185FB0C" xlink:to="loc_us-gaap_DerivativeLiabilities_FC39900B1180857D0A04AFF2C185CD06" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_BDA6CA8FFED035BDAC1BAFF2C0CAD52A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_385E36771E9C97BF8D6AAFF2C0CA0309" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_BDA6CA8FFED035BDAC1BAFF2C0CAD52A" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_385E36771E9C97BF8D6AAFF2C0CA0309" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_994A8B0FCA3D2019850DAFF2C0CA3D14" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_385E36771E9C97BF8D6AAFF2C0CA0309" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_994A8B0FCA3D2019850DAFF2C0CA3D14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_606D8791223E22248795AFF2C0CA763F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_994A8B0FCA3D2019850DAFF2C0CA3D14" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_606D8791223E22248795AFF2C0CA763F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_606D8791223E22248795AFF2C0CA763F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_994A8B0FCA3D2019850DAFF2C0CA3D14" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_606D8791223E22248795AFF2C0CA763F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_235D2FB1175F1C078E76AFF2C0CA0073" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_385E36771E9C97BF8D6AAFF2C0CA0309" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_235D2FB1175F1C078E76AFF2C0CA0073" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_532B15D7B68A188D6F97AFF2C0CAE09F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_235D2FB1175F1C078E76AFF2C0CA0073" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_532B15D7B68A188D6F97AFF2C0CAE09F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_532B15D7B68A188D6F97AFF2C0CAE09F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_235D2FB1175F1C078E76AFF2C0CA0073" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_532B15D7B68A188D6F97AFF2C0CAE09F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLocationAxis" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_449278E3E79F9F1CFEFAAFF2C0CABF54" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_385E36771E9C97BF8D6AAFF2C0CA0309" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_449278E3E79F9F1CFEFAAFF2C0CABF54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLocationDomain" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_084BEE4EAACAEC12F158AFF2C0CA1EF4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_449278E3E79F9F1CFEFAAFF2C0CABF54" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_084BEE4EAACAEC12F158AFF2C0CA1EF4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLocationDomain" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_084BEE4EAACAEC12F158AFF2C0CA1EF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_449278E3E79F9F1CFEFAAFF2C0CABF54" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_084BEE4EAACAEC12F158AFF2C0CA1EF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78D5D04349EDDCE11AB9AFF2C0CAE5E2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_385E36771E9C97BF8D6AAFF2C0CA0309" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78D5D04349EDDCE11AB9AFF2C0CAE5E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_08AF0314EBF2D2ED25C9AFF2C0CA2DC2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78D5D04349EDDCE11AB9AFF2C0CAE5E2" xlink:to="loc_us-gaap_HedgingRelationshipDomain_08AF0314EBF2D2ED25C9AFF2C0CA2DC2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_08AF0314EBF2D2ED25C9AFF2C0CA2DC2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_78D5D04349EDDCE11AB9AFF2C0CAE5E2" xlink:to="loc_us-gaap_HedgingRelationshipDomain_08AF0314EBF2D2ED25C9AFF2C0CA2DC2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DocumentAndEntityInformationDocument" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityInformationLineItems" xlink:label="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:type="locator" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntitiesTable" xlink:label="loc_dei_EntitiesTable_A4B9CE1B850100393CBFA1F09A23C0B0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntitiesTable_A4B9CE1B850100393CBFA1F09A23C0B0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_AFBF52C9D744CCB3294FA1F09A24F9EB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_A4B9CE1B850100393CBFA1F09A23C0B0" xlink:to="loc_dei_LegalEntityAxis_AFBF52C9D744CCB3294FA1F09A24F9EB" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_FB8F80EF83091DEB85F5A1F09A25EB85_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_AFBF52C9D744CCB3294FA1F09A24F9EB" xlink:to="loc_dei_EntityDomain_FB8F80EF83091DEB85F5A1F09A25EB85_default" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_FB8F80EF83091DEB85F5A1F09A25EB85" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_AFBF52C9D744CCB3294FA1F09A24F9EB" xlink:to="loc_dei_EntityDomain_FB8F80EF83091DEB85F5A1F09A25EB85" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_8D63E36EC7357F5E9E6FA1F09A27113E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntityRegistrantName_8D63E36EC7357F5E9E6FA1F09A27113E" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_290D47114F14F5E5C9B6A1F09A270A0A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntityCentralIndexKey_290D47114F14F5E5C9B6A1F09A270A0A" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate_239524E035EDFCD2DC99A1F09A2861BB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_CurrentFiscalYearEndDate_239524E035EDFCD2DC99A1F09A2861BB" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityFilerCategory" xlink:label="loc_dei_EntityFilerCategory_30D14B319101160906F6A1F09A2800BA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntityFilerCategory_30D14B319101160906F6A1F09A2800BA" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_ED0BBC918643BDCB8532A1F09A2800CA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_DocumentType_ED0BBC918643BDCB8532A1F09A2800CA" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_609FA15A57544BFECED1A1F09A2885E4" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_DocumentPeriodEndDate_609FA15A57544BFECED1A1F09A2885E4" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_dei_DocumentFiscalYearFocus_C85D65989066A9AB0FD9A1F09A28E4D4" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_DocumentFiscalYearFocus_C85D65989066A9AB0FD9A1F09A28E4D4" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_dei_DocumentFiscalPeriodFocus_92B3EBABCBAA2A1D5E2AA1F09A29B20B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_DocumentFiscalPeriodFocus_92B3EBABCBAA2A1D5E2AA1F09A29B20B" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_01993514623B12520D0CA1F09A29BA5A" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_AmendmentFlag_01993514623B12520D0CA1F09A29BA5A" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_2F7DFD650C093F2BBCFDA1F09A29E700" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_2F7DFD650C093F2BBCFDA1F09A29E700" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntitySmallBusiness" xlink:label="loc_dei_EntitySmallBusiness_703A769A7484658DB0FDA1F297B32C3D" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntitySmallBusiness_703A769A7484658DB0FDA1F297B32C3D" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityEmergingGrowthCompany" xlink:label="loc_dei_EntityEmergingGrowthCompany_D4343A509683C0387142A1F2EBCABF2B" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_F6645A1A4682A6FD416DA1F09A26D56D" xlink:to="loc_dei_EntityEmergingGrowthCompany_D4343A509683C0387142A1F2EBCABF2B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsPerShareEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDilutedLineItems" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_49469AC0EC60E3BA04D2AFF2BF276CF8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_2C12FF4C9A62F5DFDA8BAFF2BF27D90C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_49469AC0EC60E3BA04D2AFF2BF276CF8" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_2C12FF4C9A62F5DFDA8BAFF2BF27D90C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_9EEBAC89350087C93991AFF2BF273FB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_2C12FF4C9A62F5DFDA8BAFF2BF27D90C" xlink:to="loc_us-gaap_AwardTypeAxis_9EEBAC89350087C93991AFF2BF273FB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_BE309DFC7BB21798A0D6AFF2BF27BBD9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_9EEBAC89350087C93991AFF2BF273FB8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_BE309DFC7BB21798A0D6AFF2BF27BBD9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_BE309DFC7BB21798A0D6AFF2BF27BBD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_9EEBAC89350087C93991AFF2BF273FB8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_BE309DFC7BB21798A0D6AFF2BF27BBD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_B91E48E3F3598A693011AFF2BF27AEF5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_BE309DFC7BB21798A0D6AFF2BF27BBD9" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_B91E48E3F3598A693011AFF2BF27AEF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_213AE1AF4E1E0F3371F3AFF2BF27D05D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_BE309DFC7BB21798A0D6AFF2BF27BBD9" xlink:to="loc_us-gaap_EmployeeStockOptionMember_213AE1AF4E1E0F3371F3AFF2BF27D05D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_BC0910EBF0A9B64185F3AFF2BF27FDBB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_49469AC0EC60E3BA04D2AFF2BF276CF8" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_BC0910EBF0A9B64185F3AFF2BF27FDBB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_3D9E29E7B317981B623FAFF2BF27CB55" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_49469AC0EC60E3BA04D2AFF2BF276CF8" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_3D9E29E7B317981B623FAFF2BF27CB55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_64423635C2B1EC621265AFF2BF2720E7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_49469AC0EC60E3BA04D2AFF2BF276CF8" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_64423635C2B1EC621265AFF2BF2720E7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsPerShareEarningsPerShareTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDilutedLineItems" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_56C41E6902342E99A790AFF2C1569658" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_9DDFECB673FF57125D0EAFF2C1564A67" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_56C41E6902342E99A790AFF2C1569658" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_9DDFECB673FF57125D0EAFF2C1564A67" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_1B68A18B6F17926E4270AFF2C1563CB0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_9DDFECB673FF57125D0EAFF2C1564A67" xlink:to="loc_us-gaap_StatementClassOfStockAxis_1B68A18B6F17926E4270AFF2C1563CB0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_4FFC4E4DD1F057436C53AFF2C1564063_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1B68A18B6F17926E4270AFF2C1563CB0" xlink:to="loc_us-gaap_ClassOfStockDomain_4FFC4E4DD1F057436C53AFF2C1564063_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_4FFC4E4DD1F057436C53AFF2C1564063" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1B68A18B6F17926E4270AFF2C1563CB0" xlink:to="loc_us-gaap_ClassOfStockDomain_4FFC4E4DD1F057436C53AFF2C1564063" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock_7DD59C2D1FCF86FB239BAFF2C15650C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_56C41E6902342E99A790AFF2C1569658" xlink:to="loc_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock_7DD59C2D1FCF86FB239BAFF2C15650C0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsPerShareRepurchaseOfCommonStockDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_176D7D4D37864DD5D8069D30784A453E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_5199546A58A36576CBF69D3078497B40" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_176D7D4D37864DD5D8069D30784A453E" xlink:to="loc_us-gaap_StatementTable_5199546A58A36576CBF69D3078497B40" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_5C01FEEC9FBDD8F6F1C49D30784944B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_5199546A58A36576CBF69D3078497B40" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_5C01FEEC9FBDD8F6F1C49D30784944B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_C4FC95C45AFBDD877E1A9D30784ACB43_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_5C01FEEC9FBDD8F6F1C49D30784944B2" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_C4FC95C45AFBDD877E1A9D30784ACB43_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_C4FC95C45AFBDD877E1A9D30784ACB43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_5C01FEEC9FBDD8F6F1C49D30784944B2" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_C4FC95C45AFBDD877E1A9D30784ACB43" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_A10b51sharerepurchaseprogramMember" xlink:label="loc_trs_A10b51sharerepurchaseprogramMember_81E9AAFCC19A3C3EA9419D30784A89DB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_C4FC95C45AFBDD877E1A9D30784ACB43" xlink:to="loc_trs_A10b51sharerepurchaseprogramMember_81E9AAFCC19A3C3EA9419D30784A89DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" xlink:label="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_237E353771B2EE82DA429D30784AFA8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_176D7D4D37864DD5D8069D30784A453E" xlink:to="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_237E353771B2EE82DA429D30784AFA8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_2478096C919CB7A862CE9D30784B17D4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_176D7D4D37864DD5D8069D30784A453E" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_2478096C919CB7A862CE9D30784B17D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_46D964896A67F062214E9D30784B55C9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_176D7D4D37864DD5D8069D30784A453E" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_46D964896A67F062214E9D30784B55C9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwards" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsEquityAwardsNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0C090A35664142A959F4AFF2C1957955" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_611375D85EB9AF680892AFF2C195D6F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0C090A35664142A959F4AFF2C1957955" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_611375D85EB9AF680892AFF2C195D6F9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_59B4C65222D1BCB4AA09AFF2C1955215" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_611375D85EB9AF680892AFF2C195D6F9" xlink:to="loc_us-gaap_AwardTypeAxis_59B4C65222D1BCB4AA09AFF2C1955215" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_DB3B7FCA46006E5F6AA6AFF2C1959179_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_59B4C65222D1BCB4AA09AFF2C1955215" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_DB3B7FCA46006E5F6AA6AFF2C1959179_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_DB3B7FCA46006E5F6AA6AFF2C1959179" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_59B4C65222D1BCB4AA09AFF2C1955215" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_DB3B7FCA46006E5F6AA6AFF2C1959179" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_B73E7DE7D203ECA0F824AFF2C1953214" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_DB3B7FCA46006E5F6AA6AFF2C1959179" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_B73E7DE7D203ECA0F824AFF2C1953214" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0C090A35664142A959F4AFF2C1957955" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_609F9E4F56BBC585C4EAAFF2C195D69D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_609F9E4F56BBC585C4EAAFF2C195D69D" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment_75F9B9B49E64DBB7B050AFF2C19580F1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment_75F9B9B49E64DBB7B050AFF2C19580F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_505C8BE9C38CF5CA1AB0AFF2C195FFDE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_505C8BE9C38CF5CA1AB0AFF2C195FFDE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_11EB62A99C572660DD9CAFF2C1953A66" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_11EB62A99C572660DD9CAFF2C1953A66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_60F3124ED794F79E7968AFF2C195E42D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_08FB04973E47761D1613AFF2C19556C9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_60F3124ED794F79E7968AFF2C195E42D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_AD4536AB16B9B659AF98AFF2C195FE2C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0C090A35664142A959F4AFF2C1957955" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_AD4536AB16B9B659AF98AFF2C195FE2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_C55AA3B2DAC1DB92668BAFF2C195C719" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_AD4536AB16B9B659AF98AFF2C195FE2C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_C55AA3B2DAC1DB92668BAFF2C195C719" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_D8BBA14AE0EA6864FC6BAFF2C1953C0D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_AD4536AB16B9B659AF98AFF2C195FE2C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_D8BBA14AE0EA6864FC6BAFF2C1953C0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_85CD675CEB3261D63615AFF2C19588AD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_AD4536AB16B9B659AF98AFF2C195FE2C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_85CD675CEB3261D63615AFF2C19588AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_1FAE7FB7647B2FE6161CAFF2C1954BAE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_AD4536AB16B9B659AF98AFF2C195FE2C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_1FAE7FB7647B2FE6161CAFF2C1954BAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_F9CD801FA0F3A584DA2AAFF2C1955D60" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0C090A35664142A959F4AFF2C1957955" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_F9CD801FA0F3A584DA2AAFF2C1955D60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_FB2E2746B3AAE060FC1FAFF2C1953F8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_F9CD801FA0F3A584DA2AAFF2C1955D60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_FB2E2746B3AAE060FC1FAFF2C1953F8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_1CCC4C3C26E991C109C2AFF2C195C3F3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_F9CD801FA0F3A584DA2AAFF2C1955D60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_1CCC4C3C26E991C109C2AFF2C195C3F3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_2F849C62A3C315911FCEAFF2BFE4F0D9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_2F849C62A3C315911FCEAFF2BFE4F0D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_D971C782C5E48D66C259AFF2BFE4EC9E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_2F849C62A3C315911FCEAFF2BFE4F0D9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_D971C782C5E48D66C259AFF2BFE4EC9E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_D971C782C5E48D66C259AFF2BFE4EC9E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_2F849C62A3C315911FCEAFF2BFE4F0D9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_D971C782C5E48D66C259AFF2BFE4EC9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_A9705CCFB8F79AD78403AFF2BFE4BC6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_D971C782C5E48D66C259AFF2BFE4EC9E" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_A9705CCFB8F79AD78403AFF2BFE4BC6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_64369E96E1BE1426F0BAAFF2BFE4B9F4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_64369E96E1BE1426F0BAAFF2BFE4B9F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_0C6C10BD844FDD227F86AFF2BFE482B7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_64369E96E1BE1426F0BAAFF2BFE4B9F4" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_0C6C10BD844FDD227F86AFF2BFE482B7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_0C6C10BD844FDD227F86AFF2BFE482B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_64369E96E1BE1426F0BAAFF2BFE4B9F4" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_0C6C10BD844FDD227F86AFF2BFE482B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationShareBasedPaymentsMember" xlink:label="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_840C7A2F28A844599574AFF2BFE46F20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_0C6C10BD844FDD227F86AFF2BFE482B7" xlink:to="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_840C7A2F28A844599574AFF2BFE46F20" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_MetricTypeAxis" xlink:label="loc_trs_MetricTypeAxis_C29EECE19401F1AEDF0BAFF2BFE463A4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_trs_MetricTypeAxis_C29EECE19401F1AEDF0BAFF2BFE463A4" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_MetricTypeDomain" xlink:label="loc_trs_MetricTypeDomain_6F2CA2586AE1047E21E6AFF2BFE465F4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_MetricTypeAxis_C29EECE19401F1AEDF0BAFF2BFE463A4" xlink:to="loc_trs_MetricTypeDomain_6F2CA2586AE1047E21E6AFF2BFE465F4_default" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_MetricTypeDomain" xlink:label="loc_trs_MetricTypeDomain_6F2CA2586AE1047E21E6AFF2BFE465F4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_MetricTypeAxis_C29EECE19401F1AEDF0BAFF2BFE463A4" xlink:to="loc_trs_MetricTypeDomain_6F2CA2586AE1047E21E6AFF2BFE465F4" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_A3YearEpsCagrMetricMember" xlink:label="loc_trs_A3YearEpsCagrMetricMember_13F5B857EA653CBEFD7DAFF2BFE4F1D9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_6F2CA2586AE1047E21E6AFF2BFE465F4" xlink:to="loc_trs_A3YearEpsCagrMetricMember_13F5B857EA653CBEFD7DAFF2BFE4F1D9" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_TotalshareholderreturnmetricMember" xlink:label="loc_trs_TotalshareholderreturnmetricMember_6D1D29986B7DD054F683AFF2BFE4A62D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_6F2CA2586AE1047E21E6AFF2BFE465F4" xlink:to="loc_trs_TotalshareholderreturnmetricMember_6D1D29986B7DD054F683AFF2BFE4A62D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_15CDD31F31F82390EB0CAFF2BFE41286" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_srt_RangeAxis_15CDD31F31F82390EB0CAFF2BFE41286" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_B748AB10BB317ADFEF68AFF2BFE4207B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_15CDD31F31F82390EB0CAFF2BFE41286" xlink:to="loc_srt_RangeMember_B748AB10BB317ADFEF68AFF2BFE4207B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_B748AB10BB317ADFEF68AFF2BFE4207B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_15CDD31F31F82390EB0CAFF2BFE41286" xlink:to="loc_srt_RangeMember_B748AB10BB317ADFEF68AFF2BFE4207B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_9A814328624F0E11D690AFF2BFE4C89F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_B748AB10BB317ADFEF68AFF2BFE4207B" xlink:to="loc_srt_MinimumMember_9A814328624F0E11D690AFF2BFE4C89F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_1F434194A60F73072AC7AFF2BFF4BED1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_B748AB10BB317ADFEF68AFF2BFE4207B" xlink:to="loc_srt_MaximumMember_1F434194A60F73072AC7AFF2BFF4BED1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_E56DA1F3D12485DB0CC1AFF2BFF45E1B" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_us-gaap_PlanNameAxis_E56DA1F3D12485DB0CC1AFF2BFF45E1B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_E56DA1F3D12485DB0CC1AFF2BFF45E1B" xlink:to="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_E56DA1F3D12485DB0CC1AFF2BFF45E1B" xlink:to="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan1Member" xlink:label="loc_trs_Plan1Member_34BBF424AF413874FEA8AFF2BFF44F40" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan1Member_34BBF424AF413874FEA8AFF2BFF44F40" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan2Member" xlink:label="loc_trs_Plan2Member_A1E72A027F0A1397A60FAFF2BFF4D04C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan2Member_A1E72A027F0A1397A60FAFF2BFF4D04C" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan3Member" xlink:label="loc_trs_Plan3Member_0E0713693FA4D7B24F2AAFF2BFF47FA8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan3Member_0E0713693FA4D7B24F2AAFF2BFF47FA8" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan4Member" xlink:label="loc_trs_Plan4Member_2BAE2A8B2310C747FF55AFF2BFF4402F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan4Member_2BAE2A8B2310C747FF55AFF2BFF4402F" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan5Member" xlink:label="loc_trs_Plan5Member_9D0FBD619B266874A6A4AFF2BFF4A597" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan5Member_9D0FBD619B266874A6A4AFF2BFF4A597" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan7Member" xlink:label="loc_trs_Plan7Member_63CBFDE9551C5F60A220AFF2BFF4318A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan7Member_63CBFDE9551C5F60A220AFF2BFF4318A" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Plan8Member" xlink:label="loc_trs_Plan8Member_53ADFF88AAE76AA26B5BAFF2BFF4A0D9" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_C5159110FC4A7E0BDB62AFF2BFF46883" xlink:to="loc_trs_Plan8Member_53ADFF88AAE76AA26B5BAFF2BFF4A0D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_9FDC4811936C726D8A99AFF2BFF4E65F" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_us-gaap_AwardTypeAxis_9FDC4811936C726D8A99AFF2BFF4E65F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E4EA0C71DA6C561ACD88AFF2BFF4A4B4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_9FDC4811936C726D8A99AFF2BFF4E65F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E4EA0C71DA6C561ACD88AFF2BFF4A4B4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E4EA0C71DA6C561ACD88AFF2BFF4A4B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_9FDC4811936C726D8A99AFF2BFF4E65F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E4EA0C71DA6C561ACD88AFF2BFF4A4B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_BE20F8C37C0D30789284AFF2BFF458DB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E4EA0C71DA6C561ACD88AFF2BFF4A4B4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_BE20F8C37C0D30789284AFF2BFF458DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_A3BD87E1FB7940E6DDD7AFF2BFF4CC8F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E9A606B62F02AB405D80AFF2BFE42308" xlink:to="loc_us-gaap_TitleOfIndividualAxis_A3BD87E1FB7940E6DDD7AFF2BFF4CC8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_A7828AF53CF4537844CEAFF2BFF4DF20_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_A3BD87E1FB7940E6DDD7AFF2BFF4CC8F" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_A7828AF53CF4537844CEAFF2BFF4DF20_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_A7828AF53CF4537844CEAFF2BFF4DF20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_A3BD87E1FB7940E6DDD7AFF2BFF4CC8F" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_A7828AF53CF4537844CEAFF2BFF4DF20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DirectorMember" xlink:label="loc_us-gaap_DirectorMember_0ABDFEDEF39F1C5E7D09AFF2BFF479C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_A7828AF53CF4537844CEAFF2BFF4DF20" xlink:to="loc_us-gaap_DirectorMember_0ABDFEDEF39F1C5E7D09AFF2BFF479C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_2D5F103B68829858A757AFF2BFF49DD0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_2D5F103B68829858A757AFF2BFF49DD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9E63041E59BFA4CA2A19AFF2BFF494CE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9E63041E59BFA4CA2A19AFF2BFF494CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_88FF44622B18517D6CE4AFF2BFF4885C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_88FF44622B18517D6CE4AFF2BFF4885C" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_EB882B48C0F91A511BEDAFF2BFF413CA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_EB882B48C0F91A511BEDAFF2BFF413CA" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_88AB5DA4CCAFA3E62C80AFF2BFF48AE6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_88AB5DA4CCAFA3E62C80AFF2BFF48AE6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_7032CB6230196E6C9566AFF2BFF466E2" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_7032CB6230196E6C9566AFF2BFF466E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_CCCD6E937BFFECA0DCA9AFF2BFF446FB" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_CCCD6E937BFFECA0DCA9AFF2BFF446FB" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_DD74D2E19B5A9ABA7961AFF2BFF49908" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_DD74D2E19B5A9ABA7961AFF2BFF49908" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_E5F38EF8D370B59BB4F3AFF2BFF49CE3" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_E5F38EF8D370B59BB4F3AFF2BFF49CE3" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_D8D41BD7E5D0850CA340AFF2BFF41372" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_D8D41BD7E5D0850CA340AFF2BFF41372" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_856D4BEA7E27C70880A2AFF2BFF42A72" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_856D4BEA7E27C70880A2AFF2BFF42A72" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_2DF73F77E24780314BF6AFF2BFF43F14" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_2DF73F77E24780314BF6AFF2BFF43F14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_D4FEB6D0DADD67525FF7AFF2BFF42E9F" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A2F4705B74DB2999EBCEAFF2BFF4AD15" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_D4FEB6D0DADD67525FF7AFF2BFF42E9F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionActivityTableDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C03893555A4520F81507AFF2BF469F96" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C03893555A4520F81507AFF2BF469F96" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_85F57FDEF3FC87FBC3BBAFF2BF4636FA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C03893555A4520F81507AFF2BF469F96" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_85F57FDEF3FC87FBC3BBAFF2BF4636FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_0056B4D7195D2D722404AFF2BF4675AC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_85F57FDEF3FC87FBC3BBAFF2BF4636FA" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_0056B4D7195D2D722404AFF2BF4675AC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_0056B4D7195D2D722404AFF2BF4675AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_85F57FDEF3FC87FBC3BBAFF2BF4636FA" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_0056B4D7195D2D722404AFF2BF4675AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_27F7709468863173A36EAFF2BF460C76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_0056B4D7195D2D722404AFF2BF4675AC" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_27F7709468863173A36EAFF2BF460C76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_015854CEF978F99CA5AAAFF2BF46A84D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C03893555A4520F81507AFF2BF469F96" xlink:to="loc_us-gaap_AwardTypeAxis_015854CEF978F99CA5AAAFF2BF46A84D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8E0DDBBCE52A0BAB1CA9AFF2BF461799_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_015854CEF978F99CA5AAAFF2BF46A84D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8E0DDBBCE52A0BAB1CA9AFF2BF461799_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8E0DDBBCE52A0BAB1CA9AFF2BF461799" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_015854CEF978F99CA5AAAFF2BF46A84D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8E0DDBBCE52A0BAB1CA9AFF2BF461799" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_EDD02B615E13DFB2E4EFAFF2BF461DE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8E0DDBBCE52A0BAB1CA9AFF2BF461799" xlink:to="loc_us-gaap_EmployeeStockOptionMember_EDD02B615E13DFB2E4EFAFF2BF461DE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_B87EA77A6923A64DC06FAFF2BF46EC42" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_B87EA77A6923A64DC06FAFF2BF46EC42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6995DE17C801B10C9BE3AFF2BF46AC77" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6995DE17C801B10C9BE3AFF2BF46AC77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_5DA83D816670E7A14F10AFF2BF469040" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_5DA83D816670E7A14F10AFF2BF469040" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_StockOptionsVested" xlink:label="loc_trs_StockOptionsVested_2BF32551AA0B2E44147DAFF2BF463ADC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_trs_StockOptionsVested_2BF32551AA0B2E44147DAFF2BF463ADC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_325DB3B1602B91B8DAABAFF2BF46C1FB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_325DB3B1602B91B8DAABAFF2BF46C1FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_1B24B820A590830C9D9EAFF2BF46EEF1" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_1B24B820A590830C9D9EAFF2BF46EEF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_DC94C83B7BDF7E7657CEAFF2BF46CD2E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_DC94C83B7BDF7E7657CEAFF2BF46CD2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_EA10F322501BB3764D96AFF2BF464D0E" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_EA10F322501BB3764D96AFF2BF464D0E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_F6312FA870FDBE1AEA0CAFF2BF461EDF" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6EA6761BED988C9A9D59AFF2BF46C245" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_F6312FA870FDBE1AEA0CAFF2BF461EDF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityOfferingDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_54DEC0DD1F86318C3EC7AFF2C18539F6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_A149B5F60C6495C6C1E6AFF2C1859537" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_54DEC0DD1F86318C3EC7AFF2C18539F6" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_A149B5F60C6495C6C1E6AFF2C1859537" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_B5E613B3B3F532C18276AFF2C1858779" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_A149B5F60C6495C6C1E6AFF2C1859537" xlink:to="loc_us-gaap_StatementClassOfStockAxis_B5E613B3B3F532C18276AFF2C1858779" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_7E112A168BC7E5C9CE94AFF2C185E800_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B5E613B3B3F532C18276AFF2C1858779" xlink:to="loc_us-gaap_ClassOfStockDomain_7E112A168BC7E5C9CE94AFF2C185E800_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_7E112A168BC7E5C9CE94AFF2C185E800" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B5E613B3B3F532C18276AFF2C1858779" xlink:to="loc_us-gaap_ClassOfStockDomain_7E112A168BC7E5C9CE94AFF2C185E800" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_2D1D28DFB4F92EBB765CAFF2C185B7C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7E112A168BC7E5C9CE94AFF2C185E800" xlink:to="loc_us-gaap_CommonStockMember_2D1D28DFB4F92EBB765CAFF2C185B7C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_017C855849A68FA651F1AFF2C185E610" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_54DEC0DD1F86318C3EC7AFF2C18539F6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_017C855849A68FA651F1AFF2C185E610" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_DA065AA2019CD42B976DAFF2C1859A7A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_54DEC0DD1F86318C3EC7AFF2C18539F6" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_DA065AA2019CD42B976DAFF2C1859A7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_43E4B7799C3386E0B0A0AFF2C1857F88" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_54DEC0DD1F86318C3EC7AFF2C18539F6" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_43E4B7799C3386E0B0A0AFF2C1857F88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_92906A52BFBD5C091783AFF2C185E05D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_54DEC0DD1F86318C3EC7AFF2C18539F6" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_92906A52BFBD5C091783AFF2C185E05D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityOfferingNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityOfferingTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/FacilityClosuresNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_C3153312A9AC91F92A49A7BE6FF61FA3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_C3153312A9AC91F92A49A7BE6FF61FA3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_80DC207A0EF45F3DB532A7BE6FF642C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_C3153312A9AC91F92A49A7BE6FF61FA3" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_80DC207A0EF45F3DB532A7BE6FF642C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_9F720D4F9CAA9C002FF3A7BE6FF633A8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_80DC207A0EF45F3DB532A7BE6FF642C5" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_9F720D4F9CAA9C002FF3A7BE6FF633A8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_9F720D4F9CAA9C002FF3A7BE6FF633A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_80DC207A0EF45F3DB532A7BE6FF642C5" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_9F720D4F9CAA9C002FF3A7BE6FF633A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_5A9E9A30734C0563E726A7BE6FF7784B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_9F720D4F9CAA9C002FF3A7BE6FF633A8" xlink:to="loc_us-gaap_CostOfSalesMember_5A9E9A30734C0563E726A7BE6FF7784B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_62F758D9CCB5A8251732A7BE6FF7596C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_9F720D4F9CAA9C002FF3A7BE6FF633A8" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_62F758D9CCB5A8251732A7BE6FF7596C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_232625EB52CE70A00612A7BE6FF7D279" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_C3153312A9AC91F92A49A7BE6FF61FA3" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_232625EB52CE70A00612A7BE6FF7D279" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_232625EB52CE70A00612A7BE6FF7D279" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_232625EB52CE70A00612A7BE6FF7D279" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FacilityClosingBangaloreIndiaMember" xlink:label="loc_trs_FacilityClosingBangaloreIndiaMember_7F5FDCCEAD9C35CCAE14A7BE6FF84A0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7" xlink:to="loc_trs_FacilityClosingBangaloreIndiaMember_7F5FDCCEAD9C35CCAE14A7BE6FF84A0A" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FacilityClosingReynosaMexicoMember" xlink:label="loc_trs_FacilityClosingReynosaMexicoMember_334743EC966FD1F0B374A7BE6FF8A9D6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7" xlink:to="loc_trs_FacilityClosingReynosaMexicoMember_334743EC966FD1F0B374A7BE6FF8A9D6" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FacilityClosingWolverhamptonUnitedKingdomMember" xlink:label="loc_trs_FacilityClosingWolverhamptonUnitedKingdomMember_DFCA87C0C22C2F682386A7BE6FF8FAEA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_29BA89FE701260A9B249A7BE6FF7DCC7" xlink:to="loc_trs_FacilityClosingWolverhamptonUnitedKingdomMember_DFCA87C0C22C2F682386A7BE6FF8FAEA" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Totalfacilityclosureandmovecosts" xlink:label="loc_trs_Totalfacilityclosureandmovecosts_EEA890AD738AFE70F3C3A7BE6FF9D656" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_trs_Totalfacilityclosureandmovecosts_EEA890AD738AFE70F3C3A7BE6FF9D656" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FutureLeaseObligationNetofSubleaseIncome" xlink:label="loc_trs_FutureLeaseObligationNetofSubleaseIncome_276BF6219624DA5FF225A7BE6FF96B6D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_trs_FutureLeaseObligationNetofSubleaseIncome_276BF6219624DA5FF225A7BE6FF96B6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeveranceCosts1" xlink:label="loc_us-gaap_SeveranceCosts1_280516C216109F37CED8A7BE6FF9A7FF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_us-gaap_SeveranceCosts1_280516C216109F37CED8A7BE6FF9A7FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringReserveAcceleratedDepreciation" xlink:label="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_5936DBA79E052AF23193A7BE6FF96BC3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_5936DBA79E052AF23193A7BE6FF96BC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainLossOnSaleOfBusiness" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_C12C84448E7B0929A9A6A7BE6FF92D4A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_C12C84448E7B0929A9A6A7BE6FF92D4A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets1" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_6B4B2C75653AFD931AAFA7BE6FFA7D87" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6E6940211EABD8176D93A7BE6FF8B6D0" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_6B4B2C75653AFD931AAFA7BE6FFA7D87" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/FacilityClosuresRestructuringAndRelatedActivitiesDisclosureNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsGoodwillAndOtherIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_F1F1CFBA7485D649494BAFF2C1A457F4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_23BF650A8441623FED5AAFF2C1A4AA79" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_F1F1CFBA7485D649494BAFF2C1A457F4" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_23BF650A8441623FED5AAFF2C1A4AA79" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_BED44D9B7ABF638C463DAFF2C1A43453" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_23BF650A8441623FED5AAFF2C1A4AA79" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_BED44D9B7ABF638C463DAFF2C1A43453" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_BED44D9B7ABF638C463DAFF2C1A43453" xlink:to="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_BED44D9B7ABF638C463DAFF2C1A43453" xlink:to="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_PackagingReportableSegmentMember" xlink:label="loc_trs_PackagingReportableSegmentMember_3FFAB2E710C91DA5BA5DAFF2C1A47BB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039" xlink:to="loc_trs_PackagingReportableSegmentMember_3FFAB2E710C91DA5BA5DAFF2C1A47BB8" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_AerospaceDefenseReportableSegmentMember" xlink:label="loc_trs_AerospaceDefenseReportableSegmentMember_399C18F09E7B89E6A219AFF2C1A45331" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039" xlink:to="loc_trs_AerospaceDefenseReportableSegmentMember_399C18F09E7B89E6A219AFF2C1A45331" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SpecialtyProductsReportableSegmentMember" xlink:label="loc_trs_SpecialtyProductsReportableSegmentMember_78C87CB25C0187BF5E4BAFF2C1A412FF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_129E93A79E7A4654995BAFF2C1A48039" xlink:to="loc_trs_SpecialtyProductsReportableSegmentMember_78C87CB25C0187BF5E4BAFF2C1A412FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_F3A728A0AC4836F3F1BFAFF2C1A4BC14" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_F1F1CFBA7485D649494BAFF2C1A457F4" xlink:to="loc_us-gaap_GoodwillRollForward_F3A728A0AC4836F3F1BFAFF2C1A4BC14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_80A7DA9644543953AC17AFF2C1A4FCB5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_F3A728A0AC4836F3F1BFAFF2C1A4BC14" xlink:to="loc_us-gaap_Goodwill_80A7DA9644543953AC17AFF2C1A4FCB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_BD12620CE3DA3E92DBA7AFF2C1A432BE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_F3A728A0AC4836F3F1BFAFF2C1A4BC14" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_BD12620CE3DA3E92DBA7AFF2C1A432BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments" xlink:label="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_9022182AFD0CF386CCCFAFF2C1A4B584" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_F3A728A0AC4836F3F1BFAFF2C1A4BC14" xlink:to="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_9022182AFD0CF386CCCFAFF2C1A4B584" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsScheduleOfFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="trs-20180930.xsd#trs_AmortizationOfIntangibleAssetsLineItems" xlink:label="loc_trs_AmortizationOfIntangibleAssetsLineItems_09F54AF4C22FEA56ACD6AFF2C0CA03E2" xlink:type="locator" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ScheduleOfAmortizationOfIntangibleAssetsTable" xlink:label="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_0B700104E8E7EF359C15AFF2C0CA9B81" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_09F54AF4C22FEA56ACD6AFF2C0CA03E2" xlink:to="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_0B700104E8E7EF359C15AFF2C0CA9B81" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_D44485DAF29796AF2417AFF2C0CAB3D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_0B700104E8E7EF359C15AFF2C0CA9B81" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_D44485DAF29796AF2417AFF2C0CAB3D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_D4C92EEF183CCF9B38C8AFF2C0CADA9E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_D44485DAF29796AF2417AFF2C0CAB3D3" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_D4C92EEF183CCF9B38C8AFF2C0CADA9E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_D4C92EEF183CCF9B38C8AFF2C0CADA9E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_D44485DAF29796AF2417AFF2C0CAB3D3" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_D4C92EEF183CCF9B38C8AFF2C0CADA9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_7DA3E66DDD7353B01402AFF2C0CA6A6B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_D4C92EEF183CCF9B38C8AFF2C0CADA9E" xlink:to="loc_us-gaap_CostOfSalesMember_7DA3E66DDD7353B01402AFF2C0CA6A6B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_532119AF1760FED9444EAFF2C0CAF1B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_D4C92EEF183CCF9B38C8AFF2C0CADA9E" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_532119AF1760FED9444EAFF2C0CAF1B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A83F1939107B9017E722AFF2C0CA4529" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_0B700104E8E7EF359C15AFF2C0CA9B81" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A83F1939107B9017E722AFF2C0CA4529" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20AC7480DFAD580964B3AFF2C0CA2C6E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A83F1939107B9017E722AFF2C0CA4529" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20AC7480DFAD580964B3AFF2C0CA2C6E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20AC7480DFAD580964B3AFF2C0CA2C6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A83F1939107B9017E722AFF2C0CA4529" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20AC7480DFAD580964B3AFF2C0CA2C6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_75F1FD12B703F2B34E74AFF2C0CA9D49" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20AC7480DFAD580964B3AFF2C0CA2C6E" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_75F1FD12B703F2B34E74AFF2C0CA9D49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_09D308A323E347A7E2FEAFF2C0CAA0FE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20AC7480DFAD580964B3AFF2C0CA2C6E" xlink:to="loc_us-gaap_CustomerRelationshipsMember_09D308A323E347A7E2FEAFF2C0CAA0FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_8E4883D81582CA5971CCAFF2C0CA4791" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_09F54AF4C22FEA56ACD6AFF2C0CA03E2" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_8E4883D81582CA5971CCAFF2C0CA4791" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillAndOtherIntangibleAssetsScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassDetails" xlink:type="extended">
    <link:loc xlink:href="trs-20180930.xsd#trs_IntangibleAssetsExcludingGoodwillLineItems" xlink:label="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:type="locator" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable" xlink:label="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_94D02D9CEEBD7A52EBBDAFF2C02B74A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:to="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_94D02D9CEEBD7A52EBBDAFF2C02B74A0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_85A820AD9C11560D0B67AFF2C02BAE13" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_94D02D9CEEBD7A52EBBDAFF2C02B74A0" xlink:to="loc_srt_RangeAxis_85A820AD9C11560D0B67AFF2C02BAE13" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_1D234804A3174C1E9E4FAFF2C02B7387_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_85A820AD9C11560D0B67AFF2C02BAE13" xlink:to="loc_srt_RangeMember_1D234804A3174C1E9E4FAFF2C02B7387_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_1D234804A3174C1E9E4FAFF2C02B7387" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_85A820AD9C11560D0B67AFF2C02BAE13" xlink:to="loc_srt_RangeMember_1D234804A3174C1E9E4FAFF2C02B7387" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_5429ABF8D950A279F7A9AFF2C02C58B8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1D234804A3174C1E9E4FAFF2C02B7387" xlink:to="loc_srt_MinimumMember_5429ABF8D950A279F7A9AFF2C02C58B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_CD7A73A285EB8F4EC078AFF2C02C895C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1D234804A3174C1E9E4FAFF2C02B7387" xlink:to="loc_srt_MaximumMember_CD7A73A285EB8F4EC078AFF2C02C895C" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_48D5C684DC1BE2F49C7DAFF2C02C6AB7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_94D02D9CEEBD7A52EBBDAFF2C02B74A0" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_48D5C684DC1BE2F49C7DAFF2C02C6AB7" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_48D5C684DC1BE2F49C7DAFF2C02C6AB7" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE_default" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_48D5C684DC1BE2F49C7DAFF2C02C6AB7" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_UsefulLifeFiveToTwelveYearsMember" xlink:label="loc_trs_UsefulLifeFiveToTwelveYearsMember_A0DEB330CECFC6E44A84AFF2C02DB516" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE" xlink:to="loc_trs_UsefulLifeFiveToTwelveYearsMember_A0DEB330CECFC6E44A84AFF2C02DB516" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_UsefulLifeFifteenToTwentyfiveYearsMember" xlink:label="loc_trs_UsefulLifeFifteenToTwentyfiveYearsMember_69FD9C849271C2E6EFE9AFF2C02D9A71" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE" xlink:to="loc_trs_UsefulLifeFifteenToTwentyfiveYearsMember_69FD9C849271C2E6EFE9AFF2C02D9A71" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_UsefulLifeOneToFifteenYearsMember" xlink:label="loc_trs_UsefulLifeOneToFifteenYearsMember_3FA5F12A64187CD47ABAAFF2C02DC468" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE" xlink:to="loc_trs_UsefulLifeOneToFifteenYearsMember_3FA5F12A64187CD47ABAAFF2C02DC468" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_UsefulLifeSeventeenToThirtyYearsMember" xlink:label="loc_trs_UsefulLifeSeventeenToThirtyYearsMember_215CA8ED3BDE77A1D3AEAFF2C02D73E7" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_7F7D275222A05996A2FBAFF2C02C4CAE" xlink:to="loc_trs_UsefulLifeSeventeenToThirtyYearsMember_215CA8ED3BDE77A1D3AEAFF2C02D73E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1741E08796067D1CD01CAFF2C02D1554" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_94D02D9CEEBD7A52EBBDAFF2C02B74A0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1741E08796067D1CD01CAFF2C02D1554" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9133E7796DBA286D46F4AFF2C02E4F25_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1741E08796067D1CD01CAFF2C02D1554" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9133E7796DBA286D46F4AFF2C02E4F25_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9133E7796DBA286D46F4AFF2C02E4F25" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1741E08796067D1CD01CAFF2C02D1554" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9133E7796DBA286D46F4AFF2C02E4F25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_F96AAAE7C53081BAF921AFF2C02E5F34" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9133E7796DBA286D46F4AFF2C02E4F25" xlink:to="loc_us-gaap_CustomerRelationshipsMember_F96AAAE7C53081BAF921AFF2C02E5F34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_2CDAE5325516CF506E11AFF2C02ECEB8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9133E7796DBA286D46F4AFF2C02E4F25" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_2CDAE5325516CF506E11AFF2C02ECEB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_23CE178A11A263E1629DAFF2C02E4399" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_94D02D9CEEBD7A52EBBDAFF2C02B74A0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_23CE178A11A263E1629DAFF2C02E4399" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3D44FB51457E870C31D5AFF2C03E97F3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_23CE178A11A263E1629DAFF2C02E4399" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3D44FB51457E870C31D5AFF2C03E97F3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3D44FB51457E870C31D5AFF2C03E97F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_23CE178A11A263E1629DAFF2C02E4399" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3D44FB51457E870C31D5AFF2C03E97F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_749AEB94280C5C68AAA3AFF2C03EDF87" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_3D44FB51457E870C31D5AFF2C03E97F3" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_749AEB94280C5C68AAA3AFF2C03EDF87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_792ADEEF8F33781470B4AFF2C03EC692" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_792ADEEF8F33781470B4AFF2C03EC692" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_D395E406D9FE76568A2AAFF2C04DE244" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_D395E406D9FE76568A2AAFF2C04DE244" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_A49EA137B3CF6E7DA979AFF2C04D21A9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_A49EA137B3CF6E7DA979AFF2C04D21A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_B6FCA3EA324E466F9090AFF2C04DD9F4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_B6FCA3EA324E466F9090AFF2C04DD9F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_E55E1C12F4916BB7B611AFF2C04D3DAB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_0B8266160A943BE917AEAFF2C03EBFFD" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_E55E1C12F4916BB7B611AFF2C04D3DAB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/Inventories" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/InventoriesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/InventoriesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebtCreditAgreementDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_30CFF438F82DAB9E5858AB6E5C32C553" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DebtInstrumentTable_30CFF438F82DAB9E5858AB6E5C32C553" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_AEC0AA8B699D9AC3D7C5AB6E5C3274BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30CFF438F82DAB9E5858AB6E5C32C553" xlink:to="loc_us-gaap_DebtInstrumentAxis_AEC0AA8B699D9AC3D7C5AB6E5C3274BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_AEC0AA8B699D9AC3D7C5AB6E5C3274BC" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_AEC0AA8B699D9AC3D7C5AB6E5C3274BC" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_BankdebtandreceivablesfacilityMember" xlink:label="loc_trs_BankdebtandreceivablesfacilityMember_677AFEA5357A5EFF6122AB6E5C334E2D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73" xlink:to="loc_trs_BankdebtandreceivablesfacilityMember_677AFEA5357A5EFF6122AB6E5C334E2D" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_RevolvingCreditAndTermLoanFacilitiesMember" xlink:label="loc_trs_RevolvingCreditAndTermLoanFacilitiesMember_417651FB751C60090951AB6E5C33A935" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73" xlink:to="loc_trs_RevolvingCreditAndTermLoanFacilitiesMember_417651FB751C60090951AB6E5C33A935" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_D9E20F69469634321693AB6E5C339DD2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06A4D4BF211BE791DAA9AB6E5C327C73" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_D9E20F69469634321693AB6E5C339DD2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8E8F6EA93EA27FE9EA3CAB6E5C33DC07" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30CFF438F82DAB9E5858AB6E5C32C553" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8E8F6EA93EA27FE9EA3CAB6E5C33DC07" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_57D2B1CC1411CFF50086AB6E5C341D17_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8E8F6EA93EA27FE9EA3CAB6E5C33DC07" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_57D2B1CC1411CFF50086AB6E5C341D17_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_57D2B1CC1411CFF50086AB6E5C341D17" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8E8F6EA93EA27FE9EA3CAB6E5C33DC07" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_57D2B1CC1411CFF50086AB6E5C341D17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_B6DF778D4CF283E9AFE2AB6E5C34F67D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_57D2B1CC1411CFF50086AB6E5C341D17" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_B6DF778D4CF283E9AFE2AB6E5C34F67D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_1EE8509048F833F3B241AB6E5C34D1FB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30CFF438F82DAB9E5858AB6E5C32C553" xlink:to="loc_us-gaap_CreditFacilityAxis_1EE8509048F833F3B241AB6E5C34D1FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_1EE8509048F833F3B241AB6E5C34D1FB" xlink:to="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_1EE8509048F833F3B241AB6E5C34D1FB" xlink:to="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_TermloanAfacilityMember" xlink:label="loc_trs_TermloanAfacilityMember_C1C1440B18017547F896AB6E5C35FEA4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7" xlink:to="loc_trs_TermloanAfacilityMember_C1C1440B18017547F896AB6E5C35FEA4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_52F2F56B43F0AD26A20DAB6E5C35D008" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_52F2F56B43F0AD26A20DAB6E5C35D008" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_4082B0AD0F7EA91C7105AB6E5C35B1D0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_56C1F6216E710F622B47AB6E5C3472D7" xlink:to="loc_us-gaap_LetterOfCreditMember_4082B0AD0F7EA91C7105AB6E5C35B1D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_A1C00B9CF176D01B2AFDAB6E5C35FFF4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_30CFF438F82DAB9E5858AB6E5C32C553" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_A1C00B9CF176D01B2AFDAB6E5C35FFF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_011220651109DA176D70AB6E5C362517_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_A1C00B9CF176D01B2AFDAB6E5C35FFF4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_011220651109DA176D70AB6E5C362517_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_011220651109DA176D70AB6E5C362517" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_A1C00B9CF176D01B2AFDAB6E5C35FFF4" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_011220651109DA176D70AB6E5C362517" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_989D44D250AE40147D43AB6E5C36212F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_011220651109DA176D70AB6E5C362517" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_989D44D250AE40147D43AB6E5C36212F" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SeniorSecuredTermLoanMember" xlink:label="loc_trs_SeniorSecuredTermLoanMember_730DB2DC20613AAF6860AB6E5C365E4F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_011220651109DA176D70AB6E5C362517" xlink:to="loc_trs_SeniorSecuredTermLoanMember_730DB2DC20613AAF6860AB6E5C365E4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_7DC4923A9724B8EE3823AB6E5C3C2C19" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_7DC4923A9724B8EE3823AB6E5C3C2C19" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_70BFDABE9407FB1BE632AB6E5C3C8F50" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_70BFDABE9407FB1BE632AB6E5C3C8F50" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_460A7723E7FD829233CDAB6E5C3C2647" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_460A7723E7FD829233CDAB6E5C3C2647" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_CE6C7CEA9CB5E2F3518EAB6E5C3C97A1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_CE6C7CEA9CB5E2F3518EAB6E5C3C97A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases" xlink:label="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_250EE6BD957E6468C657AB6E5C3DB9C7" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_250EE6BD957E6468C657AB6E5C3DB9C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8F583037DE2D2692A324AB6E5C3D732C" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8F583037DE2D2692A324AB6E5C3D732C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_66EB09082AB8A72A7706AB6E5C3D374C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_66EB09082AB8A72A7706AB6E5C3D374C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_EFBA555D363D86E8B559AB6E5C3D9026" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_EFBA555D363D86E8B559AB6E5C3D9026" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_EAF17BCAEC2D137F2389AB6E5C3D2A35" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_EAF17BCAEC2D137F2389AB6E5C3D2A35" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_IncrementalDebtCommitmentsCapacity" xlink:label="loc_trs_IncrementalDebtCommitmentsCapacity_21C5C9639AF0D28DC262AB6E5C3D05B4" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_trs_IncrementalDebtCommitmentsCapacity_21C5C9639AF0D28DC262AB6E5C3D05B4" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_NetLeverageRatio" xlink:label="loc_trs_NetLeverageRatio_E28BC53E2D86F5ED919EAB6E5C3EEBA1" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_trs_NetLeverageRatio_E28BC53E2D86F5ED919EAB6E5C3EEBA1" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_LetterOfCreditMaximumBorrowingCapacity" xlink:label="loc_trs_LetterOfCreditMaximumBorrowingCapacity_6A8C61145EE462543630AB6E5C3E9AED" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_trs_LetterOfCreditMaximumBorrowingCapacity_6A8C61145EE462543630AB6E5C3E9AED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_73603DDB4290C66BF090AB6E5C3E6334" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_LineOfCredit_73603DDB4290C66BF090AB6E5C3E6334" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_1BD8BE6FFB099D585837AB6E5C3EFCF8" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_1BD8BE6FFB099D585837AB6E5C3EFCF8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_E1E2FA173614ABB4EEC3AB6E5C3E7F62" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_E1E2FA173614ABB4EEC3AB6E5C3E7F62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_F5A1A2257FA1FCF9A284AB6E5C3F2737" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_F5A1A2257FA1FCF9A284AB6E5C3F2737" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_LongTermDebtFairValueOfParValue" xlink:label="loc_trs_LongTermDebtFairValueOfParValue_38CF97B5196B2BD68330AB6E5C3FF79B" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_545081E9FF62656E5F29AB6E5C36E098" xlink:to="loc_trs_LongTermDebtFairValueOfParValue_38CF97B5196B2BD68330AB6E5C3FF79B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebtDebtTableDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_79FED3E60411894C1A11AFF2C023F205" xlink:type="locator" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ScheduleOfDebtInstrumentsTable" xlink:label="loc_trs_ScheduleOfDebtInstrumentsTable_88058A1BB0E37844DDACAFF2C0135879" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_79FED3E60411894C1A11AFF2C023F205" xlink:to="loc_trs_ScheduleOfDebtInstrumentsTable_88058A1BB0E37844DDACAFF2C0135879" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_B0743E989587BFE33CEFAFF2C013FA1C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_88058A1BB0E37844DDACAFF2C0135879" xlink:to="loc_us-gaap_DebtInstrumentAxis_B0743E989587BFE33CEFAFF2C013FA1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_D9304E3626C6C608FA99AFF2C0239FF5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_B0743E989587BFE33CEFAFF2C013FA1C" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_D9304E3626C6C608FA99AFF2C0239FF5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_D9304E3626C6C608FA99AFF2C0239FF5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_B0743E989587BFE33CEFAFF2C013FA1C" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_D9304E3626C6C608FA99AFF2C0239FF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_0B9051706A00E1AAE3FFAFF2C02330AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_D9304E3626C6C608FA99AFF2C0239FF5" xlink:to="loc_us-gaap_SeniorNotesMember_0B9051706A00E1AAE3FFAFF2C02330AF" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_CreditAgreementMember" xlink:label="loc_trs_CreditAgreementMember_2A9C88BF1E7B40A50FACAFF2C023F593" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_D9304E3626C6C608FA99AFF2C0239FF5" xlink:to="loc_trs_CreditAgreementMember_2A9C88BF1E7B40A50FACAFF2C023F593" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_8EE13BF2CC24793E8315AFF2C023834C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_79FED3E60411894C1A11AFF2C023F205" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_8EE13BF2CC24793E8315AFF2C023834C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_B46CEBFE901120E5385BAFF2C023E919" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_79FED3E60411894C1A11AFF2C023F205" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_B46CEBFE901120E5385BAFF2C023E919" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtCurrent" xlink:label="loc_us-gaap_DebtCurrent_C442274C52175069622FAFF2C0231507" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_79FED3E60411894C1A11AFF2C023F205" xlink:to="loc_us-gaap_DebtCurrent_C442274C52175069622FAFF2C0231507" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_0E7B89FC52DC7B6126AFAFF2C023931A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_79FED3E60411894C1A11AFF2C023F205" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_0E7B89FC52DC7B6126AFAFF2C023931A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebtFairValueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_C9A17CEAE6AAB565934BAFF2C0BA1E28" xlink:type="locator" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ScheduleOfDebtInstrumentsTable" xlink:label="loc_trs_ScheduleOfDebtInstrumentsTable_6778949D3DC3704CDFFBAFF2C0BAE34B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_C9A17CEAE6AAB565934BAFF2C0BA1E28" xlink:to="loc_trs_ScheduleOfDebtInstrumentsTable_6778949D3DC3704CDFFBAFF2C0BAE34B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2C3E3D2B8EC908EF8157AFF2C0BA5091" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_6778949D3DC3704CDFFBAFF2C0BAE34B" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2C3E3D2B8EC908EF8157AFF2C0BA5091" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D410D471D4425956F331AFF2C0BA3835_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2C3E3D2B8EC908EF8157AFF2C0BA5091" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D410D471D4425956F331AFF2C0BA3835_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D410D471D4425956F331AFF2C0BA3835" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2C3E3D2B8EC908EF8157AFF2C0BA5091" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D410D471D4425956F331AFF2C0BA3835" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_862089A2067F093810BAAFF2C0BABB25" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D410D471D4425956F331AFF2C0BA3835" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_862089A2067F093810BAAFF2C0BABB25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_16589275EF053C660A15AFF2C0BA945B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_6778949D3DC3704CDFFBAFF2C0BAE34B" xlink:to="loc_us-gaap_CreditFacilityAxis_16589275EF053C660A15AFF2C0BA945B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_414203DD8FB1BCBF6C0FAFF2C0BA6929_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_16589275EF053C660A15AFF2C0BA945B" xlink:to="loc_us-gaap_CreditFacilityDomain_414203DD8FB1BCBF6C0FAFF2C0BA6929_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_414203DD8FB1BCBF6C0FAFF2C0BA6929" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_16589275EF053C660A15AFF2C0BA945B" xlink:to="loc_us-gaap_CreditFacilityDomain_414203DD8FB1BCBF6C0FAFF2C0BA6929" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_58F7B487E57F506E7997AFF2C0BAAD7C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_414203DD8FB1BCBF6C0FAFF2C0BA6929" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_58F7B487E57F506E7997AFF2C0BAAD7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_A001FC169465071C312CAFF2C0BAA226" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_6778949D3DC3704CDFFBAFF2C0BAE34B" xlink:to="loc_us-gaap_DebtInstrumentAxis_A001FC169465071C312CAFF2C0BAA226" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_33538A7D02BD20E9DA9BAFF2C0BAA244_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_A001FC169465071C312CAFF2C0BAA226" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_33538A7D02BD20E9DA9BAFF2C0BAA244_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_33538A7D02BD20E9DA9BAFF2C0BAA244" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_A001FC169465071C312CAFF2C0BAA226" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_33538A7D02BD20E9DA9BAFF2C0BAA244" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_CreditAgreementMember" xlink:label="loc_trs_CreditAgreementMember_71E709F988F5E39EAB65AFF2C0BAAC4A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_33538A7D02BD20E9DA9BAFF2C0BAA244" xlink:to="loc_trs_CreditAgreementMember_71E709F988F5E39EAB65AFF2C0BAAC4A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_8A7C41DEFC01BAAA7B59AFF2C0BA68DD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_33538A7D02BD20E9DA9BAFF2C0BAA244" xlink:to="loc_us-gaap_SeniorNotesMember_8A7C41DEFC01BAAA7B59AFF2C0BA68DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_D4FE227A47829DE4324CAFF2C0CA79FA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_C9A17CEAE6AAB565934BAFF2C0BA1E28" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_D4FE227A47829DE4324CAFF2C0CA79FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtFairValue" xlink:label="loc_us-gaap_LongTermDebtFairValue_3DDA52134A929152827CAFF2C0CA8B92" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_C9A17CEAE6AAB565934BAFF2C0BA1E28" xlink:to="loc_us-gaap_LongTermDebtFairValue_3DDA52134A929152827CAFF2C0CA8B92" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebtLongTermDebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebtReceivablesFacilityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_402EA1DDFE845ECFAED7AFF2BFB442F0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_us-gaap_DebtInstrumentTable_402EA1DDFE845ECFAED7AFF2BFB442F0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_E9951137BA8868DFDCABAFF2BFB49734" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_402EA1DDFE845ECFAED7AFF2BFB442F0" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_E9951137BA8868DFDCABAFF2BFB49734" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1F0558C765567A455788AFF2BFB436F0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E9951137BA8868DFDCABAFF2BFB49734" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1F0558C765567A455788AFF2BFB436F0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1F0558C765567A455788AFF2BFB436F0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E9951137BA8868DFDCABAFF2BFB49734" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1F0558C765567A455788AFF2BFB436F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_575F2B119796EAE91C4FAFF2BFB43B99" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_1F0558C765567A455788AFF2BFB436F0" xlink:to="loc_us-gaap_SecuredDebtMember_575F2B119796EAE91C4FAFF2BFB43B99" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SecuredDebtMaximumBorrowingCapacity" xlink:label="loc_trs_SecuredDebtMaximumBorrowingCapacity_6BE19818CE04E7593982AFF2BFB4EF3A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_trs_SecuredDebtMaximumBorrowingCapacity_6BE19818CE04E7593982AFF2BFB4EF3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_3F59F4756254290C1774AFF2BFB4164E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_3F59F4756254290C1774AFF2BFB4164E" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage" xlink:label="loc_trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage_B6122229587791BFC92BAFF2BFB48192" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage_B6122229587791BFC92BAFF2BFB48192" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebt" xlink:label="loc_us-gaap_SecuredDebt_3EEC95B035B9E8907D5AAFF2BFB4C214" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_us-gaap_SecuredDebt_3EEC95B035B9E8907D5AAFF2BFB4C214" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_D804BFF692325C84047AAFF2BFB47722" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_D804BFF692325C84047AAFF2BFB47722" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ReceivablesFacililtyDebtAggregateCosts" xlink:label="loc_trs_ReceivablesFacililtyDebtAggregateCosts_CA7EA0954EA6395DEC1BAFF2BFB4868D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_trs_ReceivablesFacililtyDebtAggregateCosts_CA7EA0954EA6395DEC1BAFF2BFB4868D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_C9C92FDD74B9B1EB5DC3AFF2BFB4E3B8" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_C9C92FDD74B9B1EB5DC3AFF2BFB4E3B8" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_AverageliquidationperiodReceivablespool" xlink:label="loc_trs_AverageliquidationperiodReceivablespool_6603CE9BE43675490628AFF2BFB40F67" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_trs_AverageliquidationperiodReceivablespool_6603CE9BE43675490628AFF2BFB40F67" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_AverageDiscountRateReceivablesFacility" xlink:label="loc_trs_AverageDiscountRateReceivablesFacility_66E4599FB2B82FB4A0C5AFF2BFB435F9" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_AE3C2432FEAB490F000AAFF2BFB48F16" xlink:to="loc_trs_AverageDiscountRateReceivablesFacility_66E4599FB2B82FB4A0C5AFF2BFB435F9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongTermDebtSeniorNotesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_945A25C23C23C54AD13AF339432ECA05" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:to="loc_us-gaap_CreditFacilityAxis_945A25C23C23C54AD13AF339432ECA05" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_33C0241D258454485334F339432F8529_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_945A25C23C23C54AD13AF339432ECA05" xlink:to="loc_us-gaap_CreditFacilityDomain_33C0241D258454485334F339432F8529_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_33C0241D258454485334F339432F8529" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_945A25C23C23C54AD13AF339432ECA05" xlink:to="loc_us-gaap_CreditFacilityDomain_33C0241D258454485334F339432F8529" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_D635BF0C77C22A176657F339432FDE5C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_D635BF0C77C22A176657F339432FDE5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32C3E966B4C8354543FEF339432F88A2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_D635BF0C77C22A176657F339432FDE5C" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32C3E966B4C8354543FEF339432F88A2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32C3E966B4C8354543FEF339432F88A2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_D635BF0C77C22A176657F339432FDE5C" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32C3E966B4C8354543FEF339432F88A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_0784B98E1CADB4277409F33943301925" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_32C3E966B4C8354543FEF339432F88A2" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_0784B98E1CADB4277409F33943301925" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_E7D9A88C3300AB8BD18CF3394330107C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_E7D9A88C3300AB8BD18CF3394330107C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E7D9A88C3300AB8BD18CF3394330107C" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E7D9A88C3300AB8BD18CF3394330107C" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_2AA4A49E937B1B6567A5F33943306763" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E" xlink:to="loc_us-gaap_SeniorNotesMember_2AA4A49E937B1B6567A5F33943306763" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SeniorSecuredTermLoanMember" xlink:label="loc_trs_SeniorSecuredTermLoanMember_F4C238768C1912A36A50F3394331B2F5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E" xlink:to="loc_trs_SeniorSecuredTermLoanMember_F4C238768C1912A36A50F3394331B2F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_65651F97A3173F986D7BF33943319625" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8ABE75B8D9E305E129C4F3394330C50E" xlink:to="loc_us-gaap_SecuredDebtMember_65651F97A3173F986D7BF33943319625" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_59CA522A03DD150C82C4F3394331F692" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:to="loc_us-gaap_DebtInstrumentAxis_59CA522A03DD150C82C4F3394331F692" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5D11B2FA18AD617ACF55F3394331D1B0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_59CA522A03DD150C82C4F3394331F692" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5D11B2FA18AD617ACF55F3394331D1B0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5D11B2FA18AD617ACF55F3394331D1B0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_59CA522A03DD150C82C4F3394331F692" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5D11B2FA18AD617ACF55F3394331D1B0" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_5DD4D59977FDF2A02FCBF339433285ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5D11B2FA18AD617ACF55F3394331D1B0" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_5DD4D59977FDF2A02FCBF339433285ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_C170A61A64EECA4DCD3CF33943323DB4" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_C170A61A64EECA4DCD3CF33943323DB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_C170A61A64EECA4DCD3CF33943323DB4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_C170A61A64EECA4DCD3CF33943323DB4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_A8A7AB4868792AAA1F7AF33943335E5B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_A8A7AB4868792AAA1F7AF33943335E5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_5141AF382735F040C1B6F3394333FE1D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_5141AF382735F040C1B6F3394333FE1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_6D185C0343CB4142FC8DF3394333D17E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_6D185C0343CB4142FC8DF3394333D17E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodFourMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_B6690036684A37C960C9F33943333264" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_C972FE046C0F9193D890F33943327D7F" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_B6690036684A37C960C9F33943333264" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_DA6F0459903E258CFA73F3394333BB42" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_913EB1A2D60FDAF03FBFF339432E123E" xlink:to="loc_srt_RangeAxis_DA6F0459903E258CFA73F3394333BB42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_6238A2C5EB671789183BF33943347701_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_DA6F0459903E258CFA73F3394333BB42" xlink:to="loc_srt_RangeMember_6238A2C5EB671789183BF33943347701_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_6238A2C5EB671789183BF33943347701" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_DA6F0459903E258CFA73F3394333BB42" xlink:to="loc_srt_RangeMember_6238A2C5EB671789183BF33943347701" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_3615E36FF00B7D3E4FDDF33943341F5B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_3615E36FF00B7D3E4FDDF33943341F5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_A0343987D162AB251496F3394335D03E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_A0343987D162AB251496F3394335D03E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_12517BC379D61B69813CF339433580DC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_12517BC379D61B69813CF339433580DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfDebt" xlink:label="loc_us-gaap_RepaymentsOfDebt_E739B727CCB36C211807F3394335E7DC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_RepaymentsOfDebt_E739B727CCB36C211807F3394335E7DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestPaidNet" xlink:label="loc_us-gaap_InterestPaidNet_DDD69E9F52A481D18CD9F33FA1BF1E9E" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_InterestPaidNet_DDD69E9F52A481D18CD9F33FA1BF1E9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_324D52201CCBEB65D213F3394335EA88" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_324D52201CCBEB65D213F3394335EA88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_14146358EA302F839766F3394335D9DF" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_14146358EA302F839766F3394335D9DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_6EBD4F0C02FC1C6B74AEF33943365D09" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_6EBD4F0C02FC1C6B74AEF33943365D09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentDateOfFirstRequiredPayment1" xlink:label="loc_us-gaap_DebtInstrumentDateOfFirstRequiredPayment1_C22A58A355873A5D77E9F3394336DF8F" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtInstrumentDateOfFirstRequiredPayment1_C22A58A355873A5D77E9F3394336DF8F" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering" xlink:label="loc_trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering_4F8AB2E6E210C9CBBED4F339433628B5" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering_4F8AB2E6E210C9CBBED4F339433628B5" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering" xlink:label="loc_trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering_0F2ABFC97D0149035C30F33943365A79" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering_0F2ABFC97D0149035C30F33943365A79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_E3B99C2E2FC0061A7F55F33943361D67" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1CFA1556099D201D8D1FF3394334B7CB" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_E3B99C2E2FC0061A7F55F33943361D67" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/NewAccountingPronouncements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/NewAccountingPronouncementsNewAccountingPronouncementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_4F3DB02391B773371C3FAFF2BF949913" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1EE8668E50B362BCB106AFF2BF94A095" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_4F3DB02391B773371C3FAFF2BF949913" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1EE8668E50B362BCB106AFF2BF94A095" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_7E576C65808049034B13AFF2BF947FC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1EE8668E50B362BCB106AFF2BF94A095" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_7E576C65808049034B13AFF2BF947FC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_D1CAA18FC2D8C0BB4ADFAFF2BF941117_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7E576C65808049034B13AFF2BF947FC1" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_D1CAA18FC2D8C0BB4ADFAFF2BF941117_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_D1CAA18FC2D8C0BB4ADFAFF2BF941117" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7E576C65808049034B13AFF2BF947FC1" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_D1CAA18FC2D8C0BB4ADFAFF2BF941117" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_7614326986FF7C6E4C94AFF2BF94BE56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_D1CAA18FC2D8C0BB4ADFAFF2BF941117" xlink:to="loc_us-gaap_CostOfSalesMember_7614326986FF7C6E4C94AFF2BF94BE56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_47DA8FFCF98A95E5D9DDAFF2BF94AC16" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_D1CAA18FC2D8C0BB4ADFAFF2BF941117" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_47DA8FFCF98A95E5D9DDAFF2BF94AC16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1007D324ACFACEB7C27FAFF2BF949C6D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1EE8668E50B362BCB106AFF2BF94A095" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1007D324ACFACEB7C27FAFF2BF949C6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_D250209F1C8AE25CC1B5AFF2BF94E1FF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1007D324ACFACEB7C27FAFF2BF949C6D" xlink:to="loc_us-gaap_TypeOfAdoptionMember_D250209F1C8AE25CC1B5AFF2BF94E1FF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_D250209F1C8AE25CC1B5AFF2BF94E1FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1007D324ACFACEB7C27FAFF2BF949C6D" xlink:to="loc_us-gaap_TypeOfAdoptionMember_D250209F1C8AE25CC1B5AFF2BF94E1FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementMember" xlink:label="loc_us-gaap_NewAccountingPronouncementMember_752FC66FD8A46FE2A13BAFF2BF943CCF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_D250209F1C8AE25CC1B5AFF2BF94E1FF" xlink:to="loc_us-gaap_NewAccountingPronouncementMember_752FC66FD8A46FE2A13BAFF2BF943CCF" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_Nonservicecostcomponentsofnetperiodicbenefitcost" xlink:label="loc_trs_Nonservicecostcomponentsofnetperiodicbenefitcost_845C50DAB1FCEBE67113AFF2BF94E5ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_4F3DB02391B773371C3FAFF2BF949913" xlink:to="loc_trs_Nonservicecostcomponentsofnetperiodicbenefitcost_845C50DAB1FCEBE67113AFF2BF94E5ED" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_7F6BEEE3B5CDE0A5F9F3AFF2BF183F77" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_A9EA7F901A772C491179AFF2BF1846E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_7F6BEEE3B5CDE0A5F9F3AFF2BF183F77" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_A9EA7F901A772C491179AFF2BF1846E8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_4CE9B267470F11C65336AFF2BF18B37C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_A9EA7F901A772C491179AFF2BF1846E8" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_4CE9B267470F11C65336AFF2BF18B37C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_4CE9B267470F11C65336AFF2BF18B37C" xlink:to="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_4CE9B267470F11C65336AFF2BF18B37C" xlink:to="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_3F7D4CE529566484649BAFF2BF185890" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_3F7D4CE529566484649BAFF2BF185890" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember" xlink:label="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_2EA6F7DA0A0E855ED44AAFF2BF183757" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:to="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_2EA6F7DA0A0E855ED44AAFF2BF183757" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember" xlink:label="loc_trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember_3D78A6A489525EE75F48AFF2BF187D1C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:to="loc_trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember_3D78A6A489525EE75F48AFF2BF187D1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_001BB1C1EF3597109BF4AFF2BF18F440" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_001BB1C1EF3597109BF4AFF2BF18F440" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_65B1FB6864E4E9CCBB1EAFF2BF18FD06" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_20EBC38ECCD1EC72DA9DAFF2BF18AC20" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_65B1FB6864E4E9CCBB1EAFF2BF18FD06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_188E5D6902BB1F630DB2AFF2BF18BAAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_7F6BEEE3B5CDE0A5F9F3AFF2BF183F77" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_188E5D6902BB1F630DB2AFF2BF18BAAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7BF55045E20B24681113AFF2BF18CBCD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_188E5D6902BB1F630DB2AFF2BF18BAAE" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7BF55045E20B24681113AFF2BF18CBCD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_46B4538AA8331C2808EEAFF2BF188B5A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_188E5D6902BB1F630DB2AFF2BF18BAAE" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_46B4538AA8331C2808EEAFF2BF188B5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_213BAB4EC3392E3A92F7AFF2BF18DF6C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_188E5D6902BB1F630DB2AFF2BF18BAAE" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_213BAB4EC3392E3A92F7AFF2BF18DF6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_ED767F30CF63A6E8A9A2AFF2BF1869B7" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_188E5D6902BB1F630DB2AFF2BF18BAAE" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_ED767F30CF63A6E8A9A2AFF2BF1869B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossTaxAbstract" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_DD551D0FE6A82706BD43AFF2BF1878DF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_7F6BEEE3B5CDE0A5F9F3AFF2BF183F77" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_DD551D0FE6A82706BD43AFF2BF1878DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax_EBA7B597F21444D44799AFF2BF189DA9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_DD551D0FE6A82706BD43AFF2BF1878DF" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax_EBA7B597F21444D44799AFF2BF189DA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax_014A51DF838AAA844CF2AFF2BF183DDC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_DD551D0FE6A82706BD43AFF2BF1878DF" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax_014A51DF838AAA844CF2AFF2BF183DDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax_4837177272F2024376E3AFF2BF18A829" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_DD551D0FE6A82706BD43AFF2BF1878DF" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax_4837177272F2024376E3AFF2BF18A829" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossOtherComprehensiveIncomeLossTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyAndEquipmentNet" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyAndEquipmentNetDepreciationExpenseTableDetails" xlink:type="extended">
    <link:loc xlink:href="trs-20180930.xsd#trs_DepreciationExpenseLineItems" xlink:label="loc_trs_DepreciationExpenseLineItems_9108B97E1CFBD56FF9CFAFF2BFC38B22" xlink:type="locator" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ScheduleOfDepreciationExpenseTable" xlink:label="loc_trs_ScheduleOfDepreciationExpenseTable_32804426B7BB04EB31A7AFF2BFC35EC8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_DepreciationExpenseLineItems_9108B97E1CFBD56FF9CFAFF2BFC38B22" xlink:to="loc_trs_ScheduleOfDepreciationExpenseTable_32804426B7BB04EB31A7AFF2BFC35EC8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_D31B766A78037427F782AFF2BFC3995A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_32804426B7BB04EB31A7AFF2BFC35EC8" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_D31B766A78037427F782AFF2BFC3995A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_FAEEF29DF9306C1FE333AFF2BFC325A9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_D31B766A78037427F782AFF2BFC3995A" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_FAEEF29DF9306C1FE333AFF2BFC325A9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_FAEEF29DF9306C1FE333AFF2BFC325A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_D31B766A78037427F782AFF2BFC3995A" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_FAEEF29DF9306C1FE333AFF2BFC325A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_C3AC09F2AD5D2A4AB9D7AFF2BFC365A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FAEEF29DF9306C1FE333AFF2BFC325A9" xlink:to="loc_us-gaap_CostOfSalesMember_C3AC09F2AD5D2A4AB9D7AFF2BFC365A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_72B55D8CEDF069036C84AFF2BFC34F1A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FAEEF29DF9306C1FE333AFF2BFC325A9" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_72B55D8CEDF069036C84AFF2BFC34F1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_EB72D55BAD211D7B7790AFF2BFC33B53" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_32804426B7BB04EB31A7AFF2BFC35EC8" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_EB72D55BAD211D7B7790AFF2BFC33B53" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentOperatingActivitiesDomain" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_BBF534E6C32A114970EAAFF2BFC3E4C2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_EB72D55BAD211D7B7790AFF2BFC33B53" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_BBF534E6C32A114970EAAFF2BFC3E4C2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentOperatingActivitiesDomain" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_BBF534E6C32A114970EAAFF2BFC3E4C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_EB72D55BAD211D7B7790AFF2BFC33B53" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_BBF534E6C32A114970EAAFF2BFC3E4C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentContinuingOperationsMember" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_6192AA8FC8603F8D281EAFF2BFC3EFCB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_BBF534E6C32A114970EAAFF2BFC3E4C2" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_6192AA8FC8603F8D281EAFF2BFC3EFCB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_2973FADA89142EC4B298AFF2BFC3E5AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DepreciationExpenseLineItems_9108B97E1CFBD56FF9CFAFF2BFC38B22" xlink:to="loc_us-gaap_Depreciation_2973FADA89142EC4B298AFF2BFC3E5AE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyAndEquipmentNetPropertyAndEquipmentTableDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5F5D822E11FDB0C29DC4AFF2C156FAFB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_A7F359349D1D844A3F54AFF2C156BF26" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5F5D822E11FDB0C29DC4AFF2C156FAFB" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_A7F359349D1D844A3F54AFF2C156BF26" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_C33B2A671A41E78E9888AFF2C15681B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_A7F359349D1D844A3F54AFF2C156BF26" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_C33B2A671A41E78E9888AFF2C15681B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_C33B2A671A41E78E9888AFF2C15681B6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_C33B2A671A41E78E9888AFF2C15681B6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LandAndLandImprovementsMember" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_DAD0953ADCD5CC5BA431AFF2C156DE28" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_DAD0953ADCD5CC5BA431AFF2C156DE28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BuildingMember" xlink:label="loc_us-gaap_BuildingMember_04AF335CD5492439B7E0AFF2C156FE00" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57" xlink:to="loc_us-gaap_BuildingMember_04AF335CD5492439B7E0AFF2C156FE00" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_7C6661AC58FF08E4B472AFF2C1563496" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4C4BFBC2B58C9E03E84CAFF2C156AA57" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_7C6661AC58FF08E4B472AFF2C1563496" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_1B4FCDF3027073E4B658AFF2C1568A9F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5F5D822E11FDB0C29DC4AFF2C156FAFB" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_1B4FCDF3027073E4B658AFF2C1568A9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_96ED2D667A30B9EB7BFBAFF2C15649C2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5F5D822E11FDB0C29DC4AFF2C156FAFB" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_96ED2D667A30B9EB7BFBAFF2C15649C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_46ECC2BECF56D241B840AFF2C1569507" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5F5D822E11FDB0C29DC4AFF2C156FAFB" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_46ECC2BECF56D241B840AFF2C1569507" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyAndEquipmentNetTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_09AA66DFA6FCFD36E90AAFF51B7F737E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_1A6F11353B14DD9884B3AFF51B7FF6E3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_09AA66DFA6FCFD36E90AAFF51B7F737E" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_1A6F11353B14DD9884B3AFF51B7FF6E3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MajorCustomersAxis" xlink:label="loc_srt_MajorCustomersAxis_94B9317C0B7BE6AB8CE2AFF51B7FA90F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1A6F11353B14DD9884B3AFF51B7FF6E3" xlink:to="loc_srt_MajorCustomersAxis_94B9317C0B7BE6AB8CE2AFF51B7FA90F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_94B9317C0B7BE6AB8CE2AFF51B7FA90F" xlink:to="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_94B9317C0B7BE6AB8CE2AFF51B7FA90F" xlink:to="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_ConsumerMember" xlink:label="loc_trs_ConsumerMember_74A65F406377631EFCA1AFF51B7FBEE3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037" xlink:to="loc_trs_ConsumerMember_74A65F406377631EFCA1AFF51B7FBEE3" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_AerospaceMember" xlink:label="loc_trs_AerospaceMember_892F39F2E66B825B84DAAFF51B7F7CC1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037" xlink:to="loc_trs_AerospaceMember_892F39F2E66B825B84DAAFF51B7F7CC1" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_IndustrialMember" xlink:label="loc_trs_IndustrialMember_B8F0628082D0E1F1A36DAFF51B7FCFD5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037" xlink:to="loc_trs_IndustrialMember_B8F0628082D0E1F1A36DAFF51B7FCFD5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OilAndGasMember" xlink:label="loc_us-gaap_OilAndGasMember_AFD069325EBCF139232CAFF51B7F35E6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_B545EAC33A839B6FF8B9AFF51B7F1037" xlink:to="loc_us-gaap_OilAndGasMember_AFD069325EBCF139232CAFF51B7F35E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_88B277C260A6A6D188E1B0038254E12E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_09AA66DFA6FCFD36E90AAFF51B7F737E" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_88B277C260A6A6D188E1B0038254E12E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueRevenueNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueRevenuePolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueRevenueTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentInformationSegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_8259DC8DE630DB4EECC4AFF51A07EE94" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C1879EB718D946CEF10DAFF51A071938" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_8259DC8DE630DB4EECC4AFF51A07EE94" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C1879EB718D946CEF10DAFF51A071938" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_2F061155000D351DC3DEAFF51A072A89" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C1879EB718D946CEF10DAFF51A071938" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_2F061155000D351DC3DEAFF51A072A89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_30BCDD15220280961E5CAFF51A071CAC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_2F061155000D351DC3DEAFF51A072A89" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_30BCDD15220280961E5CAFF51A071CAC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_30BCDD15220280961E5CAFF51A071CAC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_2F061155000D351DC3DEAFF51A072A89" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_30BCDD15220280961E5CAFF51A071CAC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_6F57F58B893D7917D8FDAFF51A07779F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_30BCDD15220280961E5CAFF51A071CAC" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_6F57F58B893D7917D8FDAFF51A07779F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_CB9181558BACC0072E50AFF51A07237A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C1879EB718D946CEF10DAFF51A071938" xlink:to="loc_srt_ConsolidationItemsAxis_CB9181558BACC0072E50AFF51A07237A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_534498F60077F9BBF798AFF51A076A67_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_CB9181558BACC0072E50AFF51A07237A" xlink:to="loc_srt_ConsolidationItemsDomain_534498F60077F9BBF798AFF51A076A67_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_534498F60077F9BBF798AFF51A076A67" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_CB9181558BACC0072E50AFF51A07237A" xlink:to="loc_srt_ConsolidationItemsDomain_534498F60077F9BBF798AFF51A076A67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_8AC16C3B1E20706A9246AFF51A07A4E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_534498F60077F9BBF798AFF51A076A67" xlink:to="loc_us-gaap_OperatingSegmentsMember_8AC16C3B1E20706A9246AFF51A07A4E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_588DD0B0E811F22DC70FAFF51A07DCD8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_534498F60077F9BBF798AFF51A076A67" xlink:to="loc_us-gaap_CorporateNonSegmentMember_588DD0B0E811F22DC70FAFF51A07DCD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_5162277F5812B6D48AC8AFF51A0774B8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C1879EB718D946CEF10DAFF51A071938" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_5162277F5812B6D48AC8AFF51A0774B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5162277F5812B6D48AC8AFF51A0774B8" xlink:to="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5162277F5812B6D48AC8AFF51A0774B8" xlink:to="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_PackagingReportableSegmentMember" xlink:label="loc_trs_PackagingReportableSegmentMember_B227B929F3DF0F3C1863AFF51A07EF48" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C" xlink:to="loc_trs_PackagingReportableSegmentMember_B227B929F3DF0F3C1863AFF51A07EF48" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_AerospaceDefenseReportableSegmentMember" xlink:label="loc_trs_AerospaceDefenseReportableSegmentMember_412C1DD6D23E264860C9AFF51A078B0C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C" xlink:to="loc_trs_AerospaceDefenseReportableSegmentMember_412C1DD6D23E264860C9AFF51A078B0C" xlink:type="arc" />
    <link:loc xlink:href="trs-20180930.xsd#trs_SpecialtyProductsReportableSegmentMember" xlink:label="loc_trs_SpecialtyProductsReportableSegmentMember_708AEAD3F5FFB1B10C80AFF51A070A17" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C" xlink:to="loc_trs_SpecialtyProductsReportableSegmentMember_708AEAD3F5FFB1B10C80AFF51A070A17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_020F9DE9DCAF5F4B533FAFF51A0783EE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_096365953671C4FE23F5AFF51A07674C" xlink:to="loc_us-gaap_CorporateNonSegmentMember_020F9DE9DCAF5F4B533FAFF51A0783EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_8E662E8F77A900498D15B005928D5E71" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_8259DC8DE630DB4EECC4AFF51A07EE94" xlink:to="loc_us-gaap_Revenues_8E662E8F77A900498D15B005928D5E71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_31533D0A148A6361293FAFF51A07B843" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_8259DC8DE630DB4EECC4AFF51A07EE94" xlink:to="loc_us-gaap_OperatingIncomeLoss_31533D0A148A6361293FAFF51A07B843" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationAdditionalInformationAbstract" xlink:label="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_1460295D0A669EE11B02AFF51A070732" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_8259DC8DE630DB4EECC4AFF51A07EE94" xlink:to="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_1460295D0A669EE11B02AFF51A070732" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_4C768BB304351E966362AFF51A074077" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_1460295D0A669EE11B02AFF51A070732" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_4C768BB304351E966362AFF51A074077" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentInformationSegmentInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_EAD4B4087038CCA8B290C0E341077E3D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_EAD4B4087038CCA8B290C0E341077E3D" xlink:to="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_BFC27AD228686DE712D5C0E340FD7CF2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:to="loc_us-gaap_HedgingDesignationAxis_BFC27AD228686DE712D5C0E340FD7CF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_5307A9CA5381601A3971C0E340FE3644_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_BFC27AD228686DE712D5C0E340FD7CF2" xlink:to="loc_us-gaap_HedgingDesignationDomain_5307A9CA5381601A3971C0E340FE3644_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_5307A9CA5381601A3971C0E340FE3644" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_BFC27AD228686DE712D5C0E340FD7CF2" xlink:to="loc_us-gaap_HedgingDesignationDomain_5307A9CA5381601A3971C0E340FE3644" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_B06CE0E2DF614F142803C0E340FEC987" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_5307A9CA5381601A3971C0E340FE3644" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_B06CE0E2DF614F142803C0E340FEC987" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_21576EEBFF3C4912DF50C0E340FE1EDF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_21576EEBFF3C4912DF50C0E340FE1EDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_A056D467FDED79456479C0E340FFB4C8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_21576EEBFF3C4912DF50C0E340FE1EDF" xlink:to="loc_us-gaap_HedgingRelationshipDomain_A056D467FDED79456479C0E340FFB4C8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_A056D467FDED79456479C0E340FFB4C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_21576EEBFF3C4912DF50C0E340FE1EDF" xlink:to="loc_us-gaap_HedgingRelationshipDomain_A056D467FDED79456479C0E340FFB4C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetInvestmentHedgingMember" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_62B84E32DF2B38AB9755C0E340FF8ACF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_A056D467FDED79456479C0E340FFB4C8" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_62B84E32DF2B38AB9755C0E340FF8ACF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_EAFA15D363DF032054F0C0E340FF8F14" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_EAFA15D363DF032054F0C0E340FF8F14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_1EF69DEDC46D9B6E6743C0E340FFFD92_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_EAFA15D363DF032054F0C0E340FF8F14" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_1EF69DEDC46D9B6E6743C0E340FFFD92_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_1EF69DEDC46D9B6E6743C0E340FFFD92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_EAFA15D363DF032054F0C0E340FF8F14" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_1EF69DEDC46D9B6E6743C0E340FFFD92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_44789FC9ED9B5DDE91AFC0E341003CD6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_1EF69DEDC46D9B6E6743C0E340FFFD92" xlink:to="loc_us-gaap_SubsequentEventMember_44789FC9ED9B5DDE91AFC0E341003CD6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_301048F61E222B55A298C0E34105CB30" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_301048F61E222B55A298C0E34105CB30" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_E2D6B8DF02BF62D97329C0E3410524D4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_301048F61E222B55A298C0E34105CB30" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_E2D6B8DF02BF62D97329C0E3410524D4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_E2D6B8DF02BF62D97329C0E3410524D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_301048F61E222B55A298C0E34105CB30" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_E2D6B8DF02BF62D97329C0E3410524D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_E501D41F020A45F96EBEC0E34106DE56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_E2D6B8DF02BF62D97329C0E3410524D4" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_E501D41F020A45F96EBEC0E34106DE56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_2A2067E5B63B98D65E20C0E34106390C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_CEAB1601848274D9AEFDC0E340FDB488" xlink:to="loc_srt_RangeAxis_2A2067E5B63B98D65E20C0E34106390C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_618DDD6190F2EE89249BC0E341062057_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_2A2067E5B63B98D65E20C0E34106390C" xlink:to="loc_srt_RangeMember_618DDD6190F2EE89249BC0E341062057_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_618DDD6190F2EE89249BC0E341062057" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_2A2067E5B63B98D65E20C0E34106390C" xlink:to="loc_srt_RangeMember_618DDD6190F2EE89249BC0E341062057" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_C12F0575F292230BFCD9C0E341076E05" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_618DDD6190F2EE89249BC0E341062057" xlink:to="loc_srt_MinimumMember_C12F0575F292230BFCD9C0E341076E05" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_70E95873454317486A25C0E341079E93" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_618DDD6190F2EE89249BC0E341062057" xlink:to="loc_srt_MaximumMember_70E95873454317486A25C0E341079E93" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeCashReceivedOnHedge" xlink:label="loc_us-gaap_DerivativeCashReceivedOnHedge_D94A98A8AFD686FB2E7CC0E34108BCDB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_EAD4B4087038CCA8B290C0E341077E3D" xlink:to="loc_us-gaap_DerivativeCashReceivedOnHedge_D94A98A8AFD686FB2E7CC0E34108BCDB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1" xlink:label="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_EF98E514255A8121460BC0E34108C3A0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_EAD4B4087038CCA8B290C0E341077E3D" xlink:to="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_EF98E514255A8121460BC0E34108C3A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_B6F9E7D653D6C71460DEC0E341076153" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_EAD4B4087038CCA8B290C0E341077E3D" xlink:to="loc_invest_DerivativeNotionalAmount_B6F9E7D653D6C71460DEC0E341076153" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFixedInterestRate" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_D72680279A9CCB285BC4C0E341088D5B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_EAD4B4087038CCA8B290C0E341077E3D" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_D72680279A9CCB285BC4C0E341088D5B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventNotes" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_0EA70472EF016DAF0C1FC016C4BCEEFF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_65D3C7C11EDBBEC62EC6C016C4BAE82E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_0EA70472EF016DAF0C1FC016C4BCEEFF" xlink:to="loc_us-gaap_SubsequentEventTable_65D3C7C11EDBBEC62EC6C016C4BAE82E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_6B23660A8A6394AF5D4AC016C4BBA9B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_65D3C7C11EDBBEC62EC6C016C4BAE82E" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_6B23660A8A6394AF5D4AC016C4BBA9B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_79A524A4B28104C40495C016C4BBDAC7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6B23660A8A6394AF5D4AC016C4BBA9B5" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_79A524A4B28104C40495C016C4BBDAC7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_79A524A4B28104C40495C016C4BBDAC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6B23660A8A6394AF5D4AC016C4BBA9B5" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_79A524A4B28104C40495C016C4BBDAC7" xlink:type="arc" />
  </link:definitionLink>
</link:linkbase>





