auxiliary

1. not comparableHelping; giving assistance or support.

   auxiliary troops

   Synonyms: ancillary, accessory

2. not comparableSupplementary or subsidiary.

   Synonyms: accessory

3. not comparableHeld in reserve for exceptional circumstances.
4. not comparablenauticalOf a ship, having both sails and an engine.

   Synonyms: motorsailer

5. not comparablegrammarRelating to an auxiliary verb.

plural auxiliaries

1. A person or group that acts in an auxiliary manner.

   Summer “felt betrayed” that a close friend had used AI as “an auxiliary” to talk to her.

   2025 June 30, Adrienne Matei, “‘Hey man, I’m so sorry for your loss’: should you use AI to text?”, in The Guardian, →ISSN

   2 more examples

   Auxiliaries and ancillaries are comprehensive, and include a Westinghouse motor-driven recriprocating compressor used for locomotive braking and general service air, two rotary exhauster sets for train brakes when hauling passenger or fitted freight trains, and an oil-fired train heating boiler.

   1950 November, “Mixed-Traffic Diesel-Electric Locomotives for Ireland”, in Railway Magazine, page 781

   A drive to exploit the Highlands as a winter sports area, with all the necessary auxiliaries, such as chair lifts in the Cairngorms, shows increasing promise, […].

   1962 September, G. Freeman Allen, “The New Look in Scotland's Northern Division—1”, in Modern Railways, page 163

2. nauticalA sailing vessel equipped with an engine.
3. abbreviationellipsisgrammarEllipsis of auxiliary verb.

   1 more example

   The three traditionally recognized Non-modal Auxiliaries are the per- fective Auxiliary have, the progressive Auxiliary be, and the passive Auxiliary be. Perfective have is so-called because it marks the completion (hence, perfec- tion) of an action; it is followed by a VP headed by a perfective -n participle, as in: (121) The referee has [_(VP) shown him the red card]

   1988, Andrew Radford, Transformational grammar: a first course, Cambridge, UK: Cambridge University Press, page 151

4. A marching band color guard.