Webster's Revised Unabridged Dictionary · 1913

Auxiliary

Auxiliary (?; 106) , adjective

[Latin auxiliarius, from auxilium help, aid, from augere to increase.]

Conferring aid or help; helping; aiding; assisting; subsidiary; as auxiliary troops.
Collocations (2)
Auxiliary scales (Music) , the scales of relative or attendant keys. See under Attendant, a.
Auxiliary verbs (Grammar) , See Auxiliary, n., 3.

Auxiliary ({not transcribed}) , noun

1.
A helper; an assistant; a confederate in some action or enterprise.
2.
(Military) Foreign troops in the service of a nation at war; (rarely in sing.), a member of the allied or subsidiary force.
3.
(Grammar) A verb which helps to form the voices, modes, and tenses of other verbs; -- called, also, an auxiliary verb; as, have, be, may, can, do, must, shall, and will, in English; être and avoir, in French; avere and essere, in Italian; estar and haber, in Spanish.
4.
(Mathematics) A quantity introduced for the purpose of simplifying or facilitating some operation, as in equations or trigonometrical formula. — Math. Dict