Source : Webster's Revised Unabridged Dictionary (1913)

Auxiliary \Aux*il"ia*ry\ (?; 106), a. [L. auxiliarius, fr.
   auxilium help, aid, fr. augere to increase.]
   Conferring aid or help; helping; aiding; assisting;
   subsidiary; as auxiliary troops.

   {Auxiliary scales} (Mus.), the scales of relative or
      attendant keys. See under {Attendant}, a.

   {Auxiliary verbs} (Gram.). See {Auxiliary}, n., 3.