Answer:
Aggression - a hostile or "stand-offish" behavior towards another being. (i.e. dogs often bare their teeth and growl to show hostility/aggression)
Keep in mind that any intentional act of violence can be seen as aggressive. Accidents such as a car unintentionally hitting an unknowing pedestrian are not aggressive. The pedestrian is being harmed, but the driver of the car did not run them over with the intent to harm. A dog baring his teeth at an intruder before attacking is an aggressive act because the dog intends to harm the intruder.
