[ag.gres.sion] n [L aggression-, aggressio attack, fr. aggredi to attack, fr. ad- + gradi to step, go--more at grade] (1611) 1: a forceful action or procedure (as an unprovoked attack) esp. when intended to dominate or master
2: the practice of making attacks or encroachments; esp: unprovoked violation by one country of the territorial integrity of another
3: hostile, injurious, or destructive behavior or outlook esp. when caused by frustration