auxiliary

(ôg-zĭlˈyə-rē, -zĭlˈə-rē)

1. Giving assistance or support; helping.
2. Acting as a subsidiary; supplementary: the main library and its auxiliary branches.
3. Held in or used as a reserve: auxiliary troops; an auxiliary power generator.
4. Nautical Equipped with a motor as well as sails.
5. Grammar Of, relating to, or being an auxiliary verb.

1. An individual or group that assists or functions in a supporting capacity: a volunteers' auxiliary at a hospital.
2. A member of a foreign body of troops serving a country in war.
3. Grammar An auxiliary verb.
4. Nautical
   a. A sailing vessel equipped with a motor.
   b. A vessel, such as a supply ship or a tug, that is designed for and used in instances and services other than combat.