Definition of "acid"

Sour, sharp, or biting to the taste; tart; having the taste of vinegar.  examples

(figuratively) Sour-tempered.  quotations  examples

Of or pertaining to an acid; acidic.  quotations  examples

(music) Denoting a musical genre that is a distortion (as if hallucinogenic) of an existing genre, as in acid house, acid jazz, acid rock.  examples

A sour substance.  examples

(chemistry)

1. Any compound which yields H+ ions (protons) when dissolved in water; an Arrhenius acid.  examples

2. Any compound that easily donates protons to a base; a Brønsted acid.  examples

3. Any compound that can accept a pair of electrons to form a covalent bond; a Lewis acid.  examples

Any corrosive substance.  quotations  examples

(uncountable, slang) LSD, lysergic acid diethylamide.  quotations