Merriam-Webster's Collegiate® Dictionary, 11th Edition
SUPERNUMERARY
I. adjective
Etymology: Late Latin supernumerarius, from Latin super- + numerus number
Date: 1605
1. exceeding the usual, stated, or prescribed number , not enumerated among the regular components of a group and especially of a military organization, exceeding what is necessary, required, or desired, more numerous,
II. noun (plural -aries)
Date: 1639
a supernumerary person or thing, an actor employed to play a walk-on