supernumerarius

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.

sŭper-nŭmĕrārĭus, a, um, adj.,

supernumerary (post-class.): accensi, hoc est postea additi, quam fuisset legio completa, quos nunc supernumerarios vocant, Veg. Mil. 2, 19 fin. ; Aug. in Psa. 146, 9.