[C, U] (instance of) unprovoked attacking or hostility by one country against another 侵略: an act of open aggression 公然的侵略行动. 
[U] (psychology 心) hostile feelings or behaviour 敌对的情绪或行为; 攻击行动: She was always full of aggression as a child. 她自幼心中就充满了敌对情绪.