*vinegar*

n. [ OE. vinegre, F. vinaigre; vin wine (L. vinum) + aigre sour. See Wine, and Eager, a. ] 1. A sour liquid used as a condiment, or as a preservative, and obtained by the spontaneous (acetous) fermentation, or by the artificial oxidation, of wine, cider, beer, or the like. [ 1913 Webster ]

☞ The characteristic sourness of vinegar is due to acetic acid, of which it contains from three to five per cent. Wine vinegar contains also tartaric acid, citric acid, etc. [ 1913 Webster ]

2. Hence, anything sour; -- used also metaphorically. [ 1913 Webster ]

Here's the challenge: . . . I warrant there's vinegar and pepper in't. Shak. [ 1913 Webster ]

Aromatic vinegar, strong acetic acid highly flavored with aromatic substances. --
Mother of vinegar. See 4th Mother. --
Radical vinegar, acetic acid. --
Thieves' vinegar. See under Thief. --
Vinegar eel (Zool.), a minute nematode worm (Leptodera oxophila, or Anguillula acetiglutinis), commonly found in great numbers in vinegar, sour paste, and other fermenting vegetable substances; -- called also vinegar worm. --
Vinegar lamp (Chem.), a fanciful name of an apparatus designed to oxidize alcohol to acetic acid by means of platinum. --
Vinegar plant. See 4th Mother. --
Vinegar tree (Bot.), the stag-horn sumac (Rhus typhina), whose acid berries have been used to intensify the sourness of vinegar. --
Wood vinegar. See under Wood. [ 1913 Webster ]