Vinegar

n. [Fr. vinaigre, from vin, Lat. vinum, wine, and aigre, Lat. acer, sour.] 1. An acid liquor obtained from wine, cider, beer, and the like, by the acetous fermentation. ☞ The sourness of vinegar is ordinarily due to acetic acid, of which it contains a small proportion, rarely more than four or five per cent. Vinegar made from wine contains also a little tartaric acid, and a minute quantity of acetic ether, which communicates a pleasant aroma. That made from cider contains also a small proportion of malic acid. 2. Hence, any thing sour;—used also metaphorically. Aromatic vinegar, strong acetic acid highly flavored with aromatic substances.—Mother of vinegar, a thick, slimy substance which accumulates in vinegar. It consists, usually, of a compact layer upon the surface, and is produced by the aggregation of minute acotyledonous plants of the genus Ulvina, or Mycoderma (U. or M. aceti);—called also vinegar-plant. Baird.—Radical vinegar, acetic acid.—Thieves' vinegar. See THIEF.