Source : Webster's Revised Unabridged Dictionary (1913)

Supernumerary \Su`per*nu"mer*a*ry\, a. [L. supernumerarius: cf.
   OF. supernum['e]raire, F. surnum['e]raire. See {Super-}, and
   {Numerary}, {Number}.]
   1. Exceeding the number stated or prescribed; as, a
      supernumerary officer in a regiment.

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

Supernumerary \Su`per*nu"mer*a*ry\, n.; pl. {Supernumeraries}.
   1. A person or thing beyond the number stated.

   2. 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.

Source : WordNet®

supernumerary
     adj : more than is needed, desired, or required; "trying to lose
           excess weight"; "found some extra change lying on the
           dresser"; "yet another book on heraldry might be
           thought redundant"; "skills made redundant by
           technological advance"; "sleeping in the spare room";
           "supernumerary ornamentation"; "it was supererogatory
           of her to gloat"; "delete superfluous (or unnecessary)
           words"; "extra ribs as well as other supernumerary
           internal parts"; "surplus cheese distributed to the
           needy" [syn: {excess}, {extra}, {redundant}, {spare}, {supererogatory},
            {superfluous}, {surplus}]
     n : a minor actor in crowd scenes [syn: {spear carrier}, {extra}]