- A person or group that initiates an attack or invasion.
- A person who is actively hostile or assaultive.
From latin aggressor, from aggredi ("to attack").
- In the war, one country was the aggressor and the other country was the defender.
- He was arrested for assault after attacking another person without provocation, making him the aggressor.
- The aggressor's army was well-trained and well-equipped.
- The police identified him as the aggressor in the altercation.
- The aggressor nation was held responsible for starting the conflict.