1.  acerb(s = adj.all) acerbic, astringent - sour or bitter in taste;

2.  acerb(s = adj.all) acerbic, acid, acrid, bitter, blistering, caustic, sulfurous, sulphurous, virulent, vitriolic - harsh or corrosive in tone; "an acerbic tone piercing otherwise flowery prose"; "a barrage of acid comments"; "her acrid remarks make her many enemies"; "bitter words"; "blistering criticism"; "caustic jokes about political assassination, talk-show hosts and medical ethics"; "a sulfurous denunciation"; "a vitriolic critique"

   Sour, bitter, and harsh to the taste, as unripe fruit; sharp and harsh. [1913 Webster]

N  bitterness, acridness, acridity, acrimony, caustic, alkali, acerbity, gall, wormwood, bitters, astringent bitters, Angostura, aromatic bitters, sourness, pungency, alkaloids, turmeric, bitter, bitterish, acrid, acerb, acerbic, bitter as gall, bitter pill to take, sugar coating on a bitter pill.

N  sourness, acid, acidity, low pH, acetous fermentation, lactic fermentation, vinegar, verjuice, crab, alum, acetic acid, lactic acid, sour, acid, acidulous, acidulated, tart, crabbed, acetous, acetose, acerb, acetic, sour as vinegar, sourish, acescent, subacid, styptic, hard, rough, sour as a lemon, (4) Odor.