Meaning

noun a written assurance that some product or service will be provided or will meet certain specifications

noun an unconditional commitment that something will happen or that something is true

noun a collateral agreement to answer for the debt of another in case that person defaults

originFrom Old French guarantie (perhaps via a later Spanish garante), from the verb guarantir (“to protect, assure, vouch for”), ultimately from Old Frankish *warjand, *warand (“a warrant”), or from guaranty. Doublet of guaranty and warranty.

Etymology from Wiktionary, CC BY-SA 3.0