An acid is a chemical substance, usually a liquid, which contains hydrogen and can react with other substances to form salts. Some acids burn or dissolve other substances that they come into contact with.
...citric acid.
Acids in the stomach destroy the virus.
2. adjective
An acid substance contains acid.
These shrubs must have an acid, lime-free soil.
acidity (æsɪdɪti)uncountable noun
...the acidity of rainwater. [+ of]
Synonyms: sharpness, bitterness, harshness, pungency More Synonyms of acid
Synonyms: sourness, bitterness, sharpness, pungency More Synonyms of acid
3. graded adjective
An acid fruit or drink has a sour or sharp taste.
A tomatillo is a small green Mexican fruit with a delicate and slightly acid taste.
acidityuncountable noun
Taste, and adjust the acidity of the fruit by adding a pinch of sugar if required.
Synonyms: sharpness, bitterness, harshness, pungency More Synonyms of acid
Synonyms: sourness, bitterness, sharpness, pungency More Synonyms of acid
4. graded adjective
An acid remark, or acid humour, is very unkind or critical.
This comedy of contemporary manners is told with compassion and acid humour.
Synonyms: sharp, cutting, biting, severe More Synonyms of acid
acidlygraded adverb [usually ADVERB with verb, also ADVERB adjective]
'You don't know how to be a mother and you never did,' she said acidly.
Synonyms: sharply, cuttingly, bitterly, harshly More Synonyms of acid
5. uncountable noun
The drug LSD is sometimes referred to as acid.
[informal]
6. See also amino acid, hydrochloric acid, nitric acid, nucleic acid, sulphuric acid
More Synonyms of acid
acid in British English
(ˈæsɪd)
noun
1.
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. a slang name for LSD
adjective
4. chemistry
a.
of, derived from, or containing acid
an acid radical
b.
being or having the properties of an acid
sodium bicarbonate is an acid salt
5.
sharp or sour in taste
6.
cutting, sharp, or hurtful in speech, manner, etc; vitriolic; caustic
7.
(of rain, snow, etc) containing pollutant acids in solution
8.
(of igneous rocks) having a silica content of more than 60% of the total and containing at least one tenth quartz
9. metallurgy
of or made by a process in which the furnace or converter is lined with an acid material
acid steel
Derived forms
acidly (ˈacidly)
adverb
acidness (ˈacidness)
noun
acidy (ˈacidy)
adjective
Word origin
C17: (first used by Francis Bacon): from French acide or Latin acidus, from acēre to be sour or sharp
acid in American English
(ˈæsɪd)
adjective
1.
sharp and biting to the taste; sour; tart
2.
sharp or sarcastic in temperament or speech
3.
that is, or has the properties of, an acid
4.
having too heavy a concentration of acid
noun
5.
a sour substance
6. Slang
LSD
7. Chemistry
any compound that can react with a base to form a salt, the hydrogen of the acid being replaced by a positive ion; in modern theory, any substance that produces a positive ion and accepts electrons from a base to form covalent bonds: in water solution an acid tastes sour, turns blue litmus paper red, and, in the dissociation theory, produces free hydrogen ions
see also pH
SIMILAR WORDS: sour
Derived forms
acidly (ˈacidly)
adverb
acidness (ˈacidness)
noun
Word origin
L acidus, sour < IE base *a-, sharp, pointed > ear2
More idioms containing
acid
the acid test
Examples of 'acid' in a sentence
acid
Your other medicines ease the muscle spasm and empty acid from your stomach faster.
The Sun (2016)
And the one with acid rain.
Times, Sunday Times (2017)
The foods naturally cut acid in the body, which diseased organs fail to do.
The Sun (2016)
The acid test will come when we get to Germany.
Times, Sunday Times (2016)
When you digest a protein, essential amino acids are absorbed.
Times, Sunday Times (2017)
The acid test comes then.
The Sun (2016)
It contains an amino acid that converts into a chemical called serotonin and, apparently, an imbalance can affect your mood and sleep.
The Sun (2016)
Many have suffered acid or fire burns.
Times, Sunday Times (2010)
When acid from the stomach leaks up into the oesophagus it can lead to heartburn.
The Sun (2016)
This is already done when a free form amino acid capsule is taken.
Chaitow, Leon The Beat Fatigue Workbook - how to identify the causes (1988)
Do not boil too long with an acid food or it will not set.
Smith, Drew Food Watch (1994)
The soils vary from acid to basic and carry a wide range of plants.
Perring, Franklyn A Guide to Britain's Conservation Heritage (1991)
The muscles can get quite tight and it flushes out the lactic acid.
Times, Sunday Times (2009)
The process of substituting one amino acid for another in a protein is not an instantaneous one.
Wills, Christopher The Runaway Brain: the Evolution of Human Uniqueness (1993)
Another criticism is that the fruit sugar and acid in an apple are bad news for teeth.
Times, Sunday Times (2011)
This cooled the planet and caused acid rain.
The Sun (2009)
They tickle acid house classics in a folk style.
The Sun (2011)
Like somebody put acid in my drink.
Times, Sunday Times (2014)
Guilt burns like acid in my veins.
Bachmann, Susan (editor) & Barth, Melinda Between Worlds: A Reader, Rhetoric and Handbook (1995)
We all have acid in our stomachs to help digest our food.
The Sun (2009)
But sometimes it results from medication or bowel trouble such as excess acid or food intolerance.
The Sun (2011)
The next thing to explore is whether your soil is acid or alkaline.
Times, Sunday Times (2008)
But the acid test comes when you set the cost of servicing and repaying debts against the benefits of instant gratification.
Times, Sunday Times (2006)
What are its component amino acids?
Times, Sunday Times (2010)
We smoked weed, we dropped acid.
Times, Sunday Times (2011)
In other languages
acid
British English: acid /ˈæsɪd/ NOUN
An acid is a chemical, usually a liquid, that can burn your skin and cause damage to other substances.
As you can see, the acid damaged the metal bowl.
American English: acid
Arabic: حَمْض
Brazilian Portuguese: ácido
Chinese: 酸
Croatian: kiselina
Czech: kyselina
Danish: syre
Dutch: zuur
European Spanish: ácido
Finnish: happo
French: acide
German: Säure
Greek: οξύ
Italian: acido
Japanese: 酸
Korean: 산
Norwegian: syre
Polish: kwas
European Portuguese: ácido
Romanian: acid
Russian: кислота
Latin American Spanish: ácido
Swedish: syra
Thai: กรด
Turkish: asit
Ukrainian: кислота
Vietnamese: axit
All related terms of 'acid'
acid drop
a boiled sweet with a sharp taste
acid dye
a dye in which the chromophore is part of a negative ion usually applied from an acidic solution
acid-fast
(of bacteria and tissues ) resistant to decolorization by mineral acids after staining
acid jazz
a type of music, popular in the 1980s and 1990s, that combines jazz with genres such as funk , hip-hop , and electronic dance music
acid rain
Acid rain is rain polluted by acid that has been released into the atmosphere from factories and other industrial processes. Acid rain is harmful to the environment .
acid rock
a type of rock music characterized by electronically amplified bizarre instrumental effects
acid salt
a salt formed by partial replacement of the acidic hydrogen atoms of the parent acid
acid soil
a soil that gives a pH reaction of below about 6, found esp in cool moist areas where soluble bases are leached away
acid test
The acid test of something is an important aspect or result that it might have, which allows you to decide whether it is true or successful .
acid trip
a psychedelic experience induced by ingesting the hallucinogen LSD
oxo acid
any acid that contains oxygen
thio acid
an acid in which part or all of the oxygen atoms in the molecule have been replaced by sulfur atoms
uric acid
a white odourless tasteless crystalline product of protein metabolism , present in the blood and urine ; 2,6,8-trihydroxypurine. Formula: C 5 H 4 N 4 O 3
acetic acid
Acetic acid is a colourless acid. It is the main substance in vinegar .
acid attack
To attack a person or place means to try to hurt or damage them using physical violence .
acid freak
a person taking or having taken LSD regularly and heavily, such that their psychological state has been affected
acid halide
any derivative of carboxylic acid in which the hydroxyl group has been replaced by a halogen atom
Acid House
Acid house is a type of electronic dance music with a strong, repeated rhythm .
acid number
a number indicating the amount of free acid present in a substance, equal to the number of milligrams of potassium hydroxide needed to neutralize the free fatty acids present in one gram of fat or oil
acid-proof
resistant to the action of acid
acid reflux
the regurgitation of stomach acid into the oesophagus , causing heartburn
acid value
the number of milligrams of potassium hydroxide required to neutralize the free fatty acid in one gram of a fat , oil, resin , etc
adipic acid
crystalline solid used in the preparation of nylon
amino acid
Amino acids are substances containing nitrogen and hydrogen and which are found in proteins. Amino acids occur naturally in the body.
boric acid
a white soluble weakly acid crystalline solid used in the manufacture of heat-resistant glass and porcelain enamels , as a fireproofing material, and as a mild antiseptic . Formula: H 3 BO 3
bromic acid
a colourless unstable water-soluble liquid used as an oxidizing agent in the manufacture of dyes and pharmaceuticals. Formula: HBrO 3
capric acid
a crystalline fatty acid, CH 3 (CH 2 ) 8 COOH, occurring as a glyceride in natural fats and oils, used in making artificial fruit flavors, perfumes , etc.
Caro's acid
a white hygroscopic crystalline unstable oxidizing acid. Formula: H 2 SO 5
cholic acid
crystalline acid found in bile
citric acid
Citric acid is a weak acid found in many kinds of fruit, especially citrus fruit such as oranges and lemons .
cyanic acid
colourless poisonous volatile liquid acid
domoic acid
an amino acid found in shellfish that can cause food poisoning
erucic acid
crystalline fatty acid
fatty acid
any of a class of aliphatic carboxylic acids, such as palmitic acid, stearic acid, and oleic acid, that form part of a lipid molecule
folic acid
Folic acid is one of the B group of vitamins. It is found in green vegetables and fruit .
formic acid
a colourless corrosive liquid carboxylic acid found in some insects, esp ants , and many plants: used in dyeing textiles and the manufacture of insecticides and refrigerants . Formula: HCOOH
gallic acid
a colourless crystalline compound obtained from tannin : used as a tanning agent and in making inks , paper , and pyrogallol ; 3,4,5-trihydroxybenzoic acid. Formula: C 6 H 2 (OH) 3 COOH
humic acid
a brown powder consisting of organic acids, derived from humus
iodic acid
a colourless or pale yellow soluble crystalline substance that forms acidic aqueous solutions . Used as a reagent and disinfectant . Formula: HIO 3
lactic acid
Lactic acid is a type of acid which is found in sour milk and is also produced by your muscles when you have been exercising a lot .
lauric acid
dodecanoic acid
Lewis acid
a substance capable of accepting a pair of electrons from a base to form a covalent bond
lipoic acid
sulphur-containing fatty acid
maleic acid
a colourless soluble crystalline substance used to synthesize other compounds. Formula: HOOCCH:CHCOOH
malic acid
a colourless crystalline compound occurring in apples and other fruits . Formula : HOOCCH 2 CH(OH)COOH
mucic acid
colourless crystalline solid carboxylic acid
nitric acid
Nitric acid is a strong colourless acid containing nitrogen , hydrogen , and oxygen .
oleic acid
a colourless oily liquid unsaturated acid occurring, as the glyceride , in almost all natural fats used in making soaps , ointments , cosmetics , and lubricating oils. Formula: CH 3 (CH 2 ) 7 CH:CH(CH 2 ) 7 COOH