the action of a state in violating by force the rights of another state, particularly its territorial rights; an unprovoked offensive, attack, invasion, or the like: The army is prepared to stop any foreign aggression.
any offensive action, attack, or procedure; an inroad or encroachment: an aggression upon one's rights.
the practice of making assaults or attacks; offensive action in general.
Psychiatry. overt or suppressed hostility, either innate or resulting from continued frustration and directed outward or against oneself.
Origin of aggression
1605–15; < Latinaggressiōn- (stem of aggressiō), equivalent to aggress(us) (see aggress) + -iōn--ion
Related formsan·ti·ag·gres·sion, adjectivecoun·ter·ag·gres·sion, nounpre·ag·gres·sion, nounCan be confusedaggressionegression
1610s, "unprovoked attack," from French aggression (16c.), from Latin aggressionem (nominative aggressio) "a going to, an attack," noun of action from past participle stem of aggredi "to approach; attack," from ad- "to" (see ad-) + gradi (past participle gressus) "to step," from gradus "a step" (see grade). Psychological sense of "hostile or destructive behavior" first recorded 1912 in A.A. Brill's translation of Freud.
Behavior that is meant to intimidate or injure an animal of the same species or of a competing species but is not predatory. Aggression may be displayed during mating rituals or to defend territory, as by the erection of fins by fish and feathers by birds.