The Oxford Thesaurus An A-Z Dictionary of Synonyms - tart° adj.

1) sour, acidic, acidulous, acidulated, lemony, citrusy, vinegary, acetous, acescent; sharp, tangy, astringent, acerb, acerbic, acrid, bitter, pungent, piquant, harsh: Those grapes are a bit tart for my taste. 2) biting, bitter, caustic, acid, corrosive, mordant, astringent, acrimonious, trenchant, harsh, scathing, stinging, acerbic, incisive, cutting, keen,barbed, nasty, curmudgeonly, testy, crusty, abusive, virulent, sarcastic, sardonic, satiric(al) , vicious, cynical: You can rely on Henry for a tart rebuff every time.