—adj. 1. additional; supplementary; reserve: an auxiliary police force. 2. used as a substitute or reserve in case of need: The hospital has an auxiliary power system in case of a blackout. 3. (of a boat) having an engine that can be used to supplement the sails: an auxiliary yawl. 4. giving support; serving as an aid; helpful: The mind and emotions are auxiliary to each other. Passion is auxiliary to art.
—n. 1. a person or thing that gives aid of any kind; helper.
2. an organization allied with, but subsidiary to, a main body of restricted membership, esp. one composed of members' relatives: The men's club and the ladies' auxiliary were merged into one organization. 3. See auxiliary verb. 4. auxiliaries,foreign troops in the service of a nation at war.
5. Navy.a naval vessel designed for other than combat purposes, as a tug, supply ship, or transport.
6. Naut.a sailing vessel carrying an auxiliary propulsion engine or engines.