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.

noun

assailment , assault , blitz , blitzkrieg , encroachment , injury , invasion , offense , offensive , onset , onslaught , push , raid , aggressiveness , antagonism , belligerence , combativeness , destructiveness , fight , hostility , pugnacity , attempt , onrush , strike , belligerency , contentiousness , militance , militancy , attack , forceful , provocation