The Collaborative International Dictionary of English v.0.48:

Vinegar \Vin"e*gar\, v. t.
   To convert into vinegar; to make like vinegar; to render sour
   or sharp. [Obs.]
   [1913 Webster]

         Hoping that he hath vinegared his senses
         As he was bid.                           --B. Jonson.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Vinegar \Vin"e*gar\, 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]

   Note: 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]

WordNet (r) 3.0 (2006):

vinegar
    n 1: sour-tasting liquid produced usually by oxidation of the
         alcohol in wine or cider and used as a condiment or food
         preservative [syn: vinegar, acetum]
    2: dilute acetic acid

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "vinegar":
   acid, acidulant, bread-and-butter pickle, brine, chokecherry,
   crab apple, dill pickle, embalming fluid, formaldehyde,
   green apple, lemon, lime, pickle, preservative,
   preservative medium, salt, sour, sour balls, sour cream,
   sour grapes, sour pickle, sourdough, verjuice, yogurt



Easton's 1897 Bible Dictionary:

Vinegar
   Heb. hometz, Gr. oxos, Fr. vin aigre; i.e., "sour wine." The
   Hebrew word is rendered vinegar in Ps. 69:21, a prophecy
   fulfilled in the history of the crucifixion (Matt. 27:34). This
   was the common sour wine (posea) daily made use of by the Roman
   soldiers. They gave it to Christ, not in derision, but from
   compassion, to assuage his thirst. Prov. 10:26 shows that there
   was also a stronger vinegar, which was not fit for drinking. The
   comparison, "vinegar upon nitre," probably means "vinegar upon
   soda" (as in the marg. of the R.V.), which then effervesces.