1670s, "person who first attacks," from Latin aggressor, agent noun from past-participle stem of aggredi "to approach; to attempt; to attack" (see aggression).
Entries linking to aggressor
aggression n.
1610s, "unprovoked attack," from French aggression (16c., Modern French agression), from Latin aggressionem (nominative aggressio) "a going to, an attack," noun of action from 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"). The psychological sense of "hostile or destructive behavior" is recorded by 1912 in A.A. Brill's translation of Freud.