The Collaborative International Dictionary of English v.0.48:

Acid \Ac"id\, a. [L. acidus sour, fr. the root ak to be sharp:
   cf. F. acide. Cf. Acute.]
   1. Sour, sharp, or biting to the taste; tart; having the
      taste of vinegar: as, acid fruits or liquors. Also fig.:
      Sour-tempered.
      [1913 Webster]

            He was stern and his face as acid as ever. --A.
                                                  Trollope.
      [1913 Webster]

   2. Of or pertaining to an acid; as, acid reaction.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Acid \Ac"id\, n.
   1. A sour substance.
      [1913 Webster]

   2. (Chem.) One of a class of compounds, generally but not
      always distinguished by their sour taste, solubility in
      water, and reddening of vegetable blue or violet colors.
      They are also characterized by the power of destroying the
      distinctive properties of alkalies or bases, combining
      with them to form salts, at the same time losing their own
      peculiar properties. They all contain hydrogen, united
      with a more negative element or radical, either alone, or
      more generally with oxygen, and take their names from this
      negative element or radical. Those which contain no oxygen
      are sometimes called hydracids in distinction from the
      others which are called oxygen acids or oxacids.
      [1913 Webster]

   Note: In certain cases, sulphur, selenium, or tellurium may
         take the place of oxygen, and the corresponding
         compounds are called respectively sulphur acids or
         sulphacids, selenium acids, or tellurium acids.
         When the hydrogen of an acid is replaced by a positive
         element or radical, a salt is formed, and hence acids
         are sometimes named as salts of hydrogen; as hydrogen
         nitrate for nitric acid, hydrogen sulphate for
         sulphuric acid, etc. In the old chemistry the name acid
         was applied to the oxides of the negative or
         nonmetallic elements, now sometimes called anhydrides.
         [1913 Webster]

WordNet (r) 3.0 (2006):

acid
    adj 1: harsh or corrosive in tone; "an acerbic tone piercing
           otherwise flowery prose"; "a barrage of acid comments";
           "her acrid remarks make her many enemies"; "bitter
           words"; "blistering criticism"; "caustic jokes about
           political assassination, talk-show hosts and medical
           ethics"; "a sulfurous denunciation"; "a vitriolic
           critique" [syn: acerb, acerbic, acid, acrid,
           bitter, blistering, caustic, sulfurous,
           sulphurous, virulent, vitriolic]
    2: being sour to the taste [syn: acidic, acid, acidulent,
       acidulous]
    3: having the characteristics of an acid; "an acid reaction"
    n 1: any of various water-soluble compounds having a sour taste
         and capable of turning litmus red and reacting with a base
         to form a salt
    2: street name for lysergic acid diethylamide [syn: acid,
       back breaker, battery-acid, dose, dot, Elvis,
       loony toons, Lucy in the sky with diamonds, pane,
       superman, window pane, Zen]

The Free On-line Dictionary of Computing (19 January 2023):

ACID

    A mnemonic for the properties a transaction
   should have to satisfy the Object Management Group
   Transaction Service specifications.  A transaction should be
   Atomic, its result should be Consistent, Isolated
   (independent of other transactions) and Durable (its effect
   should be permanent).

   The Transaction Service specifications which part of the
   Object Services, an adjunct to the CORBA specifications.

   (1997-05-15)