- The definition of an auxiliary verb is used to change the tense or voice of other verbs.
An example of an auxiliary verb is "be", "do" or "have."
auxiliary verb definition by Webster's New World
auxiliary verb definition by American Heritage Dictionary
auxiliary verb - Cultural Definition
A “helping” verb that modifies the main verb, as in “Gail can win,” “Gail did win,” “Gail could have won.” A question often begins with an auxiliary verb: “Did Gail win?” “Could Gail lose?” The various forms of the verbs can, have, is, and does frequently act as auxiliaries.