1. A person, usually a professional combatant, a captive, or a slave, trained to entertain the public by engaging in mortal combat with another person, or a wild animal, in the ancient Roman arena; now more like a person engaged in a controversy or debate, especially in public; a disputant.
2. In ancient Rome, a professional fighter who fought another combatant, or a wild animal, in public entertainments which took place in an arena.

Often gladiators were criminals, or slaves, who were equipped with nets, nooses, swords, or other weapons for battle to entertain Romans in the circuses.