Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings

to fall; to drop; to go down; (of the sun or moon) to set; (of a tide) to go out; to decline; to sink

(literary) set pattern; old rut; a stereotypical style or formula often used to describe unoriginal writing or artistic works