auxˌiliary ˈverb BrE AmE noun [countable]
a verb that is used with another verb to show its tense, ↑ person , ↑ mood etc. In English the auxiliary verbs are ‘be’, ‘do’, and ‘have’ (as in ‘I am running’, ‘I didn’t go’, ‘they have gone’), and all the ↑ modal s