Auxiliary

Conferring aid or help; helping; aiding; assisting; subsidiary; as auxiliary troops.

A helper; an assistant; a confederate in some action or enterprise.

Foreign troops in the service of a nation at war; (rarely in sing.), a member of the allied or subsidiary force.

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; etre and avoir, in French; avere and essere, in Italian; estar and haber, in Spanish.

A quantity introduced for the purpose of simplifying or facilitating some operation, as in equations or trigonometrical formulae.

furnishing added support; "an ancillary pump"; "an adjuvant discipline to forms of mysticism"; "The mind and emotions are auxiliary to each other"