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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-02-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002053424</rptOwnerCik>
            <rptOwnerName>KONG-PICARELLO JENNIFER</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TEREX CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>301 MERRITT 7</rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06851</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President, CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $ .01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2025-02-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>28256</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28256</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares represent 28,256 restricted stock units (&quot;RSUs&quot;) issued by Issuer pursuant to one of its long-term incentive plans. Each RSU represents a contingent right to receive one share of the Issuer's common stock. The RSUs will vest as follows: 1/3 on February 28, 2026; 1/3 on February 28, 2027; and 1/3 on February 28, 2028, subject to the Reporting Person's continued employment with the Issuer on each such vesting date.</footnote>
        <footnote id="F2">Total includes reported restricted stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Scott J. Posner by power of attorney</signatureName>
        <signatureDate>2025-03-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2025-02-28
0
0000097216
TEREX CORP
TEX
0002053424
KONG-PICARELLO JENNIFER
C/O TEREX CORPORATION
301 MERRITT 7
NORWALK
CT
06851
0
1
0
0
Senior Vice President, CFO
0
Common Stock, $ .01 par value
2025-02-28
4
A
0
28256
0
A
28256
D
The shares represent 28,256 restricted stock units ("RSUs") issued by Issuer pursuant to one of its long-term incentive plans. Each RSU represents a contingent right to receive one share of the Issuer's common stock. The RSUs will vest as follows: 1/3 on February 28, 2026; 1/3 on February 28, 2027; and 1/3 on February 28, 2028, subject to the Reporting Person's continued employment with the Issuer on each such vesting date.
Total includes reported restricted stock units.
/s/ Scott J. Posner by power of attorney
2025-03-04