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 If your car has a 3.5mm jack, there would be an auxiliary cable for audio, too. Nicole Nguyen, WSJ, 24 Apr. 2022 So what does an auxiliary police officer actually do? Linda Gandee, cleveland, 21 Mar. 2022 There are additional storage compartments on the bottom of the camper as well as two power-retractable awnings, LED auxiliary lighting, and even an exterior shower. Eric Stafford, Car and Driver, 27 Apr. 2022 The shooting happened Sunday afternoon during the exercise at a Taylor city park for the city’s volunteer auxiliary police program. From Usa Today Network And Wire Reports, USA TODAY, 26 Apr. 2022 Devin Booker was putting the finishing touches on knocking down corner 3s inside the University of New Orleans’ auxiliary gym before ending Saturday's practice with free throws. Duane Rankin, The Arizona Republic, 23 Apr. 2022 During the early stages of the pandemic, French began using her Airstream as an auxiliary kitchen for her 40-seat seasonal restaurant, parking the camper just outside to help expand the physical space. Hannah Selinger, Outside Online, 23 Apr. 2022 According to naval expert H.I. Sutton, the eight-ship salvage flotilla includes the world’s oldest active warship, the Russian auxiliary Kommuna. David Axe, Forbes, 22 Apr. 2022 When it cannot be avoided, the hostess should apologize, make provisions so those excluded can see and hear, and ask close friends to sit in the second room, possibly designating one as an auxiliary hostess. Washington Post, 21 Apr. 2022 Recent Examples on the Web: Noun 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 Monetary donations are also welcome and cards will be purchased by the auxiliary in your name. Linda Mcintosh, San Diego Union-Tribune, 22 Nov. 2021 Butler’s time in the Marines coincided with its transformation from a Navy auxiliary to having its own identity and purpose as a colonial infantry. Patrick Iber, The New Republic, 11 Jan. 2022 Monetary donations are also welcome and cards will be purchased by the auxiliary in your name. Linda Mcintosh, San Diego Union-Tribune, 22 Nov. 2021 Monetary donations are also welcome and cards will be purchased by the auxiliary in your name. Linda Mcintosh, San Diego Union-Tribune, 22 Nov. 2021 Monetary donations are also welcome and cards will be purchased by the auxiliary in your name. Linda Mcintosh, San Diego Union-Tribune, 22 Nov. 2021 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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Dictionary Entries Near auxiliary



auxiliary cell

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Last Updated

16 May 2022

Cite this Entry

“Auxiliary.” Dictionary, Merriam-Webster, Accessed 25 May. 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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