vinegar (n.)

early 14c., from Old French vinaigre "vinegar," from vin "wine" (from Latin vinum; see wine (n.)) + aigre "sour" (see eager). In Latin, it was vinum acetum "wine turned sour," acetum for short (see acetic), also used figuratively for "wit, shrewdness;" and compare Greek oxos "wine vinegar," which is related to oxys "sharp" (from PIE root *ak- "be sharp, rise (out) to a point, pierce"). Related: Vinegary; vinegarish.