acetic (adj.)

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.

U.S. name for "para-acetylaminophenol," 1960, composed of syllables from the chemical name: acetyl, a derivative of acetic (q.v.; also see acetylene) + amino- + phenol. In Britain, the same substance is paracetamol.