- a boxer or other contestant of the lightest competitive class, especially a professional boxer weighing up to 112 pounds (51 kg).
- a professional boxer weighing not more than 112 pounds (51 kg)
- an amateur boxer weighing 48–51 kg (106–112 pounds)
- (as modifier)a flyweight contest
- (in Olympic wrestling) a wrestler weighing not more than 115 pounds (52 kg)