acid

[ as-id ]

noun

1. Chemistry. 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. LSD ¹.

adjective

1. Chemistry.
   1. belonging or pertaining to acids or the anhydrides of acids.
   2. having only a part of the hydrogen of an acid replaced by a metal or its equivalent:

      an acid phosphate.

   3. having a pH value of less than 7. Compare 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.

   Synonyms: tart, vitriolic, biting, acerbic

4. Geology. containing much silica.
5. Metallurgy. 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. Compare basic ( def 3 ).

acid

/ ˈæsɪd /

noun

1. See Lewis acid
   any substance that dissociates in water to yield a sour corrosive solution containing hydrogen ions, having a pH of less than 7, and turning litmus red See also Lewis acid
2. a sour-tasting substance
3. See LSD
   a slang name for LSD

adjective

1. chem
   1. of, derived from, or containing acid

      an acid radical

   2. being or having the properties of an acid

      sodium bicarbonate is an acid salt

2. sharp or sour in taste
3. cutting, sharp, or hurtful in speech, manner, etc; vitriolic; caustic
4. (of rain, snow, etc) containing pollutant acids in solution
5. (of igneous rocks) having a silica content of more than 60% of the total and containing at least one tenth quartz
6. metallurgy of or made by a process in which the furnace or converter is lined with an acid material

   acid steel

acid

/ ăs′ĭd /

1. Any of a class of compounds that form hydrogen ions when dissolved in water, and whose aqueous solutions react with bases and certain metals to form salts. Acids turn blue litmus paper red and have a pH of less than 7. Their aqueous solutions have a sour taste.
2. Compare base

acid

1. A sour-tasting material (usually in a solution ) that dissolves metals and other materials. Technically, a material that produces positive ions in solution. An acid is the opposite of a base and has a pH of 0 to 7. A given amount of an acid added to the same amount of a base neutralizes the base, producing water and a salt . Common vinegar, for example, is a weak solution of acetic acid.

Notes

Figuratively, acid applies to anything sour or biting; for example, an “acid wit” is sharp and unpleasant.

Derived Forms

• ˈacidy, adjective
• ˈacidly, adverb
• ˈacidness, noun

Other Words From

• acid·ly adverb
• acid·ness noun
• non·acid noun adjective
• pre·acid adjective
• pre·acid·ness noun
• semi·acid adjective

Word History and Origins

Origin of acid¹

First recorded in 1620–30; from Latin acidus “sour,” akin to ācer “sharp,” acētum “vinegar”; acescent, acicula

Word History and Origins

Origin of acid¹

C17: (first used by Francis Bacon): from French acide or Latin acidus, from acēre to be sour or sharp

Idioms and Phrases

Idioms

1. put on the acid, Australian Slang. to importune someone, as for money, sexual favors, or confidential information.

Synonym Study

Acid, astringent are terms used figuratively of wit or humor. Acid suggests a sharp, biting, or ill-natured quality: an acid joke about an opponent. Astringent connotes severity but usually also a bracing quality, as of something applied with curative intent: astringent criticism.

Example Sentences

I write the lyrics and work with Murv Douglas from Lords of Acid.

From The Daily Beast

During the height of his disenchantment, he visited his hometown where an old friend gave him some liquid acid.

From The Daily Beast

Eggs, he says, are a good source of cysteine, an amino acid that helps the liver break down alcohol faster.

From The Daily Beast

This at-home blood test kit gives a full reading of antioxidant, fatty acid, or vitamin panels.

From The Daily Beast

The recent spate of acid attacks on women is only the latest manifestation of this dangerous trend.

From The Daily Beast

There are a number of bacilli, called acid-fast bacilli, which stain in the same way as the tubercle bacillus.

From Project Gutenberg

The amount of the other purin bodies together is about one-tenth that of uric acid.

From Project Gutenberg

Uric acid is decreased before an attack of gout and increased afterward, but its etiologic relation is still uncertain.

From Project Gutenberg

An increase is also noted in the uric-acid diathesis and in diseases accompanied by respiratory insufficiency.

From Project Gutenberg

Indol is absorbed and oxidized into indoxyl, which combines with potassium and sulphuric acid and is thus excreted.

From Project Gutenberg