A sour substance.

(chemistry) A compound that can yield h+ ions in water, easily donate protons to a base, and accept a pair of electrons to form a covalent bond.

Any corrosive substance.

(uncountable, slang) LSD, lysergic acid diethylamide.

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

(figurative) Sour-tempered.

Of or pertaining to an acid; acidic.

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