tart (3)EnglishOxford American Thesaurustart3 adjective 1 cook a few tart apples: sour, sharp, sharp-tasting, tangy, bitter, acid, acidic, zesty, piquant, pungent, strong, harsh, unsweetened, vinegary, lemony, citrus, burning, acrid, acetic; rare acidulous, acetous. ▷antonyms sweet. 2 she regretted her rather tart reply: acerbic, sharp, biting, cutting, keen, stinging, mordant, astringent, caustic, trenchant, incisive, pointed, piercing, bitter, barbed, scathing, sarcastic, sardonic, acrimonious, nasty, rude, vicious, spiteful, venomous, wounding. ▷antonyms kind.