Warranty

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Middle English: from Anglo-Norman French warantie, variant of garantie (see guaranty). Early use was as a legal term denoting a covenant annexed to a conveyance of property, in which the vendor affirmed the security of the title.

wiktionary

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From Old French warrantie, Old Northern French variant of Old French guarantie (Modern French garantie). Doublet of guarantee and guaranty. More at warrant.

etymonline

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warranty (n.)

mid-14c., legal term for various types of clauses in real estate transactions, from Anglo-French and Old North French warantie "protection, defense, safeguard" (Old French garantie), from warant (see warrant (n.)).