Pronunciation: (as'id), [key]
1. Chem.a compound usually having a sour taste and capable of neutralizing alkalis and reddening blue litmus paper, containing hydrogen that can be replaced by a metal or an electropositive group to form a salt, or containing an atom that can accept a pair of electrons from a base. Acids are proton donors that yield hydronium ions in water solution, or electron-pair acceptors that combine with electron-pair donors or bases.
2. a substance with a sour taste.
3. something, as a remark or piece of writing, that is sharp, sour, or ill-natured: His criticism was pure acid.
4. Slang.See LSD (def. 2).
5. put on the acid, Australian Slang.to importune someone, as for money, sexual favors, or confidential information.
a. belonging or pertaining to acids or the anhydrides of acids.
b. having only a part of the hydrogen of an acid replaced by a metal or its equivalent: an acid phosphate.
c. having a pH value of less than 7. Cf. alkaline (def. 4).
2. sharp or biting to the taste; tasting like vinegar; sour: acid fruits.
3. sharp, biting, or ill-natured in mood, manner, etc.: an acid remark; an acid wit.
4. Geol.containing much silica.
5. Metall.noting, pertaining to, or made by a process in which the lining of the furnace, or the slag that is present, functions as an acid in high-temperature reactions in taking electrons from oxide ions: usually a siliceous material, as sand or ganister. Cf. basic (def. 3).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.