a person who attacks others in order to hurt or kill, either physically or by shouting at them using bad language;
a person who has attacked someone, often used in police records and in the court of law;
an aggressor; an assaulter;
a group of people or a country that attacks another group or country in order to takeover it; an invader,
When she was walking home from a near-by park in the evening, Sara was attacked by some assailants who tried to rob her of her purse.
John was badly injured when he tried to fight off his two assailants who wore ski masks and were armed with hockey sticks.