1. [n]  a powerful hallucinogenic drug
2. [n]  
3. [adj]  (chemistry) containing acid; "an acid taste"
4. [adj]  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"

1. \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.
            He was stern and his face as acid as ever. --A.
                                                  Trollope.
   2. Of or pertaining to an acid; as, acid reaction.
   

2. \Ac"id\, n.
   1. A sour substance.
   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}.
   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.
   

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.

1. Arrhenius acid: any chemical that increases the number of free hydrogen ions (H⁺) when they're added to a water-based solution. The more free hydrogens produced, the stronger the acid.
2. Brönsted or Brönsted-Lowry acid: any chemical that acts as a proton donor in a chemical reaction.
3. Lewis acid: any chemical that accepts two electrons to form a covalent bond during a chemical reaction.