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.