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.
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.
2. Hence, anything sour; used also metaphorically. Here's the challenge: . . . I warrant there's vinegar and pepper in't. (Shak) aromatic vinegar, strong acetic acid highly flavored with aromatic substances. Mother of vinegar. See 4th Mother. Radical vinegar, acetic acid. Thieves' vinegar. See thief.
(Science: chemistry) Vinegar eel, a fanciful name of an apparatus designed to oxidize alcohol to acetic acid by means of platinum. Vinegar plant. See 4th mother.
(Science: botany) Vinegar tree, the stag-horn sumac (rhus typhina), whose acid berries have been used to intensify the sourness of vinegar. Wood vinegar. See Wood.
Origin: OE. Vinegre, F. Vinaigre; vin wine (L. Vinum) _ aigre sour. See Wine, and Eager.