Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.
  • noun A substance that yields hydrogen ions when dissolved in water.
  • noun A substance that can act as a proton donor.
  • noun A substance that can accept a pair of electrons to form a covalent bond.
  • noun A substance having a sour taste.
  • noun The quality of being sarcastic, bitter, or scornful.
  • adjective Of, relating to, or containing an acid.
  • adjective Having a high concentration of acid.
  • adjective Having the characteristics of an acid.
  • adjective Having a pH of less than 7.
  • adjective Having a relatively high concentration of hydrogen ions.
  • adjective Geology Containing a large proportion of silica.
  • adjective Having a sour taste. synonym: sour.
  • adjective Biting, sarcastic, or scornful.

from The Century Dictionary.

  • Sour, sharp, or biting to the taste; tasting like vinegar: as, acid fruits or liquors.
  • noun Originally, a substance possessing a sour taste like that of vinegar; in modern chemical use, a name given to a large number of compounds which do not necessarily possess this property.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Sour, sharp, or biting to the taste; tart; having the taste of vinegar: as, acid fruits or liquors. Also fig.: Sour-tempered.
  • adjective Of or pertaining to an acid.
  • noun A sour substance.
  • noun (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective Sour, sharp, or biting to the taste; tart; having the taste of vinegar.
  • adjective figuratively Sour-tempered.
  • adjective Of or pertaining to an acid; acidic.
  • adjective music Denoting a musical genre that is a distortion (as if hallucinogenic) of an existing genre, as in acid house, acid jazz, acid rock.
  • noun A sour substance.
  • noun chemistry Any of several classes of compound having the following properties:-
  • noun slang lysergic acid diethylamide

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun street name for lysergic acid diethylamide
  • noun 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
  • adjective harsh or corrosive in tone
  • adjective being sour to the taste
  • adjective having the characteristics of an acid

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[From Latin acidus, sour, from acēre, to be sour; see ak- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From French acide, from Latin acidus ("sour, acid"), from aceō ("I am sour").

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Examples

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  • 1906 US Railway Assn. Standard Cipher Code meaning "action taken is satisfactory".

    January 19, 2013