(tär′tər) noun
1. An acid substance deposited from grape juice during fermentation as a pinkish sediment; crude potassium bitartrate. See ARGOL, CREAM OF TARTAR.
2. Dent. A yellowish incrustation on the teeth, chiefly calcium phosphate. [<F tartre <LL tartarum <Med. Gk. tartaron,? <Arabic]

(tär′tər) noun
1. Tatar.
2. A person of intractable or savage temper; also, especially in the phrase to catch a Tartar, an opponent who turns out to be unexpectedly formidable: also tar′tar.
—adjective Of or pertaining to the Tatars of Tartary. [<F Tartare <LL Tartarus <Persian Tātar Tatar; prob. infl. by L Tartarus Hell]

(tär′tər) Obs.
Tartarus.