acid

The definition of acid is sour or sharp in taste, or having a pH of under 7 in chemistry.

(noun)

Lemon juice and vinegar are each an example of an acid.

Acid is defined as something that has a sour taste, or something that has a pH of less than 7 in chemistry.

(adjective)

Lemon is an example of an acid substance.

See acid in Webster's New World College Dictionary

adjective

Origin: L acidus, sour < IE base *a-, sharp, pointed > ear

noun

a sour substance
Slang LSD
Chem. 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

Related Forms:

See acid in American Heritage Dictionary 4

noun

Chemistry
a. 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.
b. A substance that yields hydrogen ions when dissolved in water.
c. A substance that can act as a proton donor.
d. A substance that can accept a pair of electrons to form a covalent bond.
A substance having a sour taste.
The quality of being sarcastic, bitter, or scornful: wrote with acid about her first marriage.
Slang See LSD¹.

adjective

Chemistry
a. Of, relating to, or containing an acid.
b. Having a high concentration of acid.
c. Having the characteristics of an acid.
a. Having a pH of less than 7.
b. Having a relatively high concentration of hydrogen ions.
Geology Containing a large proportion of silica: acid rocks.
Having a sour taste. See Synonyms at sour.
Biting, sarcastic, or scornful: an acid wit; an acid tone of voice.