Auxiliar

a. [Lat. auxiliaris, auxiliarius, from auxilium, help, aid, from augere, to increase; Fr. auxiliaire.] Conferring aid or help; helping; aiding; assisting; subsidiary; as, auxiliary troops. “To seek auxiliary force.” Pope. “An auxiliary verb.” Murray.

Auxiliary scales (Mus.), the six keys or scales, consisting of any key major, with its relative minor, and the relative keys of each.