1791, "characterized by aggression, tending to make the first attack," with -ive + Latin aggress-, past participle stem of aggredi "to approach; to attempt; to attack," from ad "to" (see ad-) + gradi (past participle gressus) "to step," from gradus "a step," figuratively "a step toward something, an approach" (from PIE root *ghredh- "to walk, go"). In psychological use from 1913, first in translations of Freud. Colloquial meaning "self-assertive, pushy" is from 1931. Related: Aggressively; aggressiveness.
