Synonyms for Supernumerary (same or very similar meaning)
WordNet sense 1 (a minor actor in crowd scenes):
extra, spear carrierWordNet sense 2 (more than is needed, desired, or required):
excess, redundant, spare, supererogatory, superfluous, surplusWordNet sense 3 (not necessary):
unnecessary, unneededFrom the ODE community, based on WordNetadd/edit