a person who tries to harm or who has harmed others physically, usually using weapons;
an assailant; a mugger;
a player in a ball game who advances (goes) into the opponent’s area with force to make a goal or get a point,
When he was attacked in the park by some attackers, his girlfriend rushed to the nearest telephone booth and called the police for help.
The detective saw the dead body of a young woman, and he immediately understood that there were more than one attacker and she had fought with her attackers for quite some time before they finally killed her.
The old man was unable to describe the facial features of his attacker because the latter wore a mask.