<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-03-20</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000097216</issuerCik>
        <issuerName>TEREX CORP</issuerName>
        <issuerTradingSymbol>TEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001656422</rptOwnerCik>
            <rptOwnerName>GARRISON JOHN L JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TEREX CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>45 GLOVER AVENUE</rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06850</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Former DIR, Chairman and CEO</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.01</value>
            </securityTitle>
            <transactionDate>
                <value>2024-03-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>59094</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>60.07</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>380834</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.01</value>
            </securityTitle>
            <transactionDate>
                <value>2024-03-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15906</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>61.74</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>364928</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents average sales price. Shares sold at various prices ranging from $60.00 to $60.45. Mr. Garrison will provide upon request by the SEC staff, Terex Corporation or a security holder of Terex Corporation, the full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F2">Ownership includes shares received as a dividend.</footnote>
        <footnote id="F3">Represents average sales price. Shares sold at various prices ranging from $60.22 to $62.20. Mr. Garrison will provide upon request by the SEC staff, Terex Corporation or a security holder of Terex Corporation, the full information regarding the number of shares sold at each separate price.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Scott J. Posner, by power of attorney</signatureName>
        <signatureDate>2024-03-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2024-03-20
1
0000097216
TEREX CORP
TEX
0001656422
GARRISON JOHN L JR
C/O TEREX CORPORATION
45 GLOVER AVENUE
NORWALK
CT
06850
0
0
0
1
Former DIR, Chairman and CEO
0
Common Stock, par value $.01
2024-03-20
4
S
0
59094
60.07
D
380834
D
Common Stock, par value $.01
2024-03-21
4
S
0
15906
61.74
D
364928
D
Represents average sales price. Shares sold at various prices ranging from $60.00 to $60.45. Mr. Garrison will provide upon request by the SEC staff, Terex Corporation or a security holder of Terex Corporation, the full information regarding the number of shares sold at each separate price.
Ownership includes shares received as a dividend.
Represents average sales price. Shares sold at various prices ranging from $60.22 to $62.20. Mr. Garrison will provide upon request by the SEC staff, Terex Corporation or a security holder of Terex Corporation, the full information regarding the number of shares sold at each separate price.
/s/Scott J. Posner, by power of attorney
2024-03-22