Auxiliary is defined as something or someone used in a supporting role or used in reserve.(adjective)
An example of an auxiliary generator is one that gives power to a building when the main generators stop working.
See auxiliary in Webster's New World College Dictionary
Origin: L auxiliaris, helpful < auxilium, aid < pp. of augere, to increase: see wax
noun pl. auxiliaries
See auxiliary in American Heritage Dictionary 4
Origin: Middle English
Origin: , from Latin auxiliārius
Origin: , from auxilium, help; see aug- in Indo-European roots.
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