aux·​il·​ia·​ry | \ ȯg-ˈzil-yə-rē How to pronounce auxiliary (audio) , -ˈzil-rē, -ˈzi-lə- How to pronounce auxiliary (audio) \

Definition of auxiliary

 (Entry 1 of 2)

1a : offering or providing help
b : functioning in a subsidiary capacity an auxiliary branch of the state university
2 of a verb : accompanying another verb and typically expressing person, number, mood, or tense In "I will go," the word "will" is an auxiliary verb.
3a : supplementary a telescope with its auxiliary apparatus
b : constituting a reserve an auxiliary power plant an auxiliary police force
4 of a boat : equipped with sails and a supplementary inboard engine an auxiliary sloop


plural auxiliaries

Definition of auxiliary (Entry 2 of 2)

1a : an auxiliary person, group, or device specifically : a member of a foreign force serving a nation at war
b : a Roman Catholic titular bishop assisting a diocesan bishop and not having the right of succession

called also auxiliary bishop

2 : a sailing boat or ship equipped with a supplementary inboard engine
3 grammar : an auxiliary verb

Synonyms & Antonyms for auxiliary

Synonyms: Adjective

Antonyms: Adjective

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Auxiliary is used in a wide range of capacities in English to describe a person or thing that assists another. A fire department may bring in auxiliary units, for example, to battle a tough blaze, or a sailboat may be equipped with auxiliary engines to supply propulsion when the wind disappears. In grammar, an auxiliary verb assists another (main) verb to express person, number, mood, or tense, such as have in "They have been informed." The Latin source of auxiliary is auxilium, meaning "help."

Examples of auxiliary in a Sentence

Adjective Travelers have also been griping about a lack of air-conditioning while planes are on the tarmac—even after delays stretch for hours. Airlines blame the problem on a breakdown of a plane's auxiliary power unit. — Darren Everson, Wall Street Journal, 8 Aug. 2007 However, on March 1, 1896, Italian forces underwent a stunning defeat at Adwa, where they fought against the warriors of the Abyssinian emperor, Menelik. Some five thousand Italian troops and two thousand native auxiliary troops had been killed or captured, and the colony had been lost. — Mirella Tenderini et al., The Duke of the Abruzzi, 1997 The rotund 6'1", 235-pound object of their affections hasn't played a day of major league baseball, he dresses in the auxiliary locker room, and he isn't even listed on Boston's 40-man roster. But after a resplendent summer last year at Triple A Pawtucket and a winter of panegyrics from a giddy Boston press, first baseman Maurice Samuel (Mo) Vaughn, 23, has arrived as a "real" rookie who everyone in Red Sox-land hopes is the real thing. — Nicholas Dawidoff, Sports Illustrated, 1 Apr. 1991 a sailboat with an auxiliary engine the auditorium has an auxiliary cooling system used only on particularly sweltering days Noun In 1944 Forrestal also began a program of sending black enlisted men to serve in a limited number of fleet auxiliaries. These were still not warships, but they were seagoing vessels and closer to the fighting Navy than the small harbor-defense craft and harbor auxiliaries that had initially been open to black crews. The Golden Thirteen, 1993 Roman cavalry was poorly developed; they relied on wings, called alae, of horsemen supplied by their auxiliaries. The favorite Roman battle formation was of a triple line of cohorts with alae sweeping the flanks. — Kenneth P. Czech, MHQ : The Quarterly Journal of Military History, Autumn 1992 See More
Recent Examples on the Web: Adjective The $90 device that connects to a car's auxiliary power outlet, docks to the dashboard, and enables Spotify listening was doomed by a combination of limited demand and resource issues. Scharon Harding, Ars Technica, 27 July 2022 Featuring a 58-inch cable, this heated travel blanket can be plugged into your car through the standard 12V auxiliary power outlet. Hannah Drown, cleveland, 1 Dec. 2020 Fitted out with Smittylite bumpers and roll bar and a total of six KC HiLites auxiliary lights, this truck is all dressed up like the movies. Brendan Mcaleer, Car and Driver, 9 Sep. 2022 That’s the temperature at which the park begins shutting down auxiliary services, like ranger talks and outdoor programs. Julie Jag, The Salt Lake Tribune, 1 Sep. 2022 According to the suit filed Monday in Boston, Archbishop Paul Fitzpatrick Russell, 63, currently one of five auxiliary bishops in the Archdiocese of Detroit, raped the boy while Russell was a priest in the Archdiocese of Boston from 1989 to 1990. Niraj Warikoo, Detroit Free Press, 3 Aug. 2022 The arena, except for the overhead scoreboard and some auxiliary lights, went dark for a few moments. Tom Noie, The Indianapolis Star, 22 Mar. 2021 The Echo Auto connects to your phone via the Alexa app and plays from your vehicle's speakers via Bluetooth or auxiliary input. Charles Dryer And Collin Morgan, Car and Driver, 7 July 2022 Echo Auto connects to the Alexa app on your smartphone and can connect to your car speakers using an auxiliary input or your phone’s Bluetooth connection. Maren Estrada, BGR, 17 June 2021 Recent Examples on the Web: Noun The auxiliary donated 26 hours to the project, Doutt said. Linda G. Kramer, cleveland, 22 Aug. 2022 To promote effective interaction with the male auxiliary. Helaine Williams, Arkansas Online, 17 July 2022 Games will be played at six gyms in Shelbyville — Collins High School main, Collins High School auxiliary, Marnel Moorman School, West Middle School, Shelby Christian Church and First Baptist Church. Jason Frakes, The Courier-Journal, 16 June 2022 The Assisteens are an auxiliary of the Assistance League, and are open to teens in grades 9-12 who attend school in Carlsbad, Del Mar, Solana Beach and Encinitas. Laura Groch, San Diego Union-Tribune, 29 May 2022 Scotland Yard only began employing a rudimentary fingerprint system in 1894, and only as an auxiliary to anthropometrics, which identified criminals by physical characteristics like skull width and foot length. Roy Schwartz, CNN, 20 May 2022 The march to Kyiv on the western bank of the Dnipro River began and ended in Chernobyl for the 31st and 36th Combined Arms Armies of the Russian military, which traveled with an auxiliary of special forces and ethnic Chechen combatants. New York Times, 8 Apr. 2022 Past presidents of the auxiliary from 1996 to 2021 include Dixie Bales, Vikki Ramey, Alicia Sullivan, Marge Stogdill, Karen Gallagher, Angela Gothard, Helen Parsons, Debbie Knight, Vera Bayliss, Carol Sanford, Nita Rodriguez and Joyce Cerimele. Linda Mcintosh, San Diego Union-Tribune, 16 Feb. 2022 In such instances, whistle-blowers can occasionally function as an unofficial auxiliary, doing things that government investigators do not have the resources—or the legal authority—to do. Patrick Radden Keefe, The New Yorker, 17 Jan. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'auxiliary.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of auxiliary


15th century, in the meaning defined at sense 1a


1567, in the meaning defined at sense 1a

History and Etymology for auxiliary


Latin auxiliaris, from auxilium help; akin to Latin augēre to increase — more at eke


derivative of auxiliary entry 1

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Time Traveler for auxiliary

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The first known use of auxiliary was in the 15th century

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auxiliary cell

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Last Updated

25 Sep 2022

Cite this Entry

“Auxiliary.” Dictionary, Merriam-Webster, Accessed 30 Sep. 2022.

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More Definitions for auxiliary


aux·​il·​ia·​ry | \ ȯg-ˈzi-lyə-rē How to pronounce auxiliary (audio) , -ˈzi-lə-rē, -ˈzil-rē \

Kids Definition of auxiliary

 (Entry 1 of 2)

: available to provide something extra an auxiliary engine


plural auxiliaries

Kids Definition of auxiliary (Entry 2 of 2)

1 : a group that provides assistance


aux·​il·​ia·​ry | \ ȯg-ˈzil-yə-rē How to pronounce auxiliary (audio) , -ˈzil-(ə-)rē How to pronounce auxiliary (audio) \

Medical Definition of auxiliary

 (Entry 1 of 2)

: serving to supplement or assist auxiliary springs in a dental appliance



Medical Definition of auxiliary (Entry 2 of 2)

1 : one who assists or serves another person especially in dentistry
2 : an organization that assists (as by donations or volunteer services) the work especially of a hospital

More from Merriam-Webster on auxiliary

Nglish: Translation of auxiliary for Spanish Speakers

Britannica English: Translation of auxiliary for Arabic Speakers Encyclopedia article about auxiliary


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