fermentation, lactic fermentation. vinegar, verjuice†, crab, alum; acetic acid, lactic acid. V. be sour; sour, turn sour &c adj.; set the teeth on edge. render sour &c adj.; acidify, acidulate. Adj. sour; acid, acidulous, acidulated; tart, crabbed; acetous, acetose†; acerb, acetic; sour as vinegar, sourish, acescent†, subacid [Chem]; styptic, hard, rough. Phr. sour as a lemon. (4) Odor