What does "vinegar" mean?

Vinegar: 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 under Thief. -- Vinegar eel (Zoöl.), 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.