In general use, auxiliary describes someone or something available to provide extra help, power, etc., when it is needed. In linguistics, an auxiliary verb (also called a “helping verb”) is used with another verb to do things like show a verb’s tense or form a question. In nautical contexts, auxiliary can describe a sailboat equipped with a supplementary inboard engine, or a vessel that provides supplementary assistance to other ships.
offering or providing help.
an individual or group that assists or functions in a supporting capacity [n AUXILIARIES]
Providing supplementary or additional help and support
(of equipment) Held in reserve
(of troops) Engaged in the service of a nation at war but not part of the regular army, and often of foreign origin
(of a sailing vessel) Equipped with a supplementary engine
a helper, a subordinate also AUXILIAR [n AUXILIARIES]