late 14c., "to decorate, adorn, beautify," also in Middle English "equip (a place) for defense; arm (oneself) for battle; prepare to defend," from Old French garniss-, present participle stem of garnir "provide, furnish; fortify, reinforce" (11c.), from Frankish *warnjan, from Proto-Germanic *warnon "be cautious, guard, provide for" (cognates: Old High German warnon "to take heed," Old English warnian "to take warning, beware;" see weir, and compare warn).Sense evolution is from "arm oneself" to "fit out" to "embellish," which was the earliest meaning in English. Culinary sense of "to decorate a dish for the table" predominated after c.1700. Older meaning survives in legal sense of "to warn or serve notice of attachment of funds" (1570s). Related: Garnished; garnishing.

late 14c., "set of tableware" (probably a dozen; usually pewter), from garnish, v.. Sense of "embellishments to food" is from 1670s.