Supernumerary

Exceeding the number stated or prescribed; as, a supernumerary officer in a regiment.

Exceeding a necessary, usual, or required number or quality; superfluous; as, supernumerary addresses; supernumerary expense.

A person or thing beyond the number stated.

A person or thing beyond what is necessary or usual; especially, a person employed not for regular service, but only to fill the place of another in case of need; specifically, in theaters, a person who is not a regular actor, but is employed to appear in a stage spectacle.