adj. & n.
adj. 1 (of a person or thing) that gives help. 2 (of services or equipment) subsidiary, additional.
n. (pl. -ies) 1 an auxiliary person or thing. 2 (in pl.) Mil. auxiliary troops. 3 Gram. an auxiliary verb. auxiliary troops Mil. foreign or allied troops in a belligerent nation's service. auxiliary verb Gram. one used in forming tenses, moods, and voices of other verbs.
[ L auxiliarius f. auxilium help ]