auxiliary

American  

[awg-zil-yuh-ree, -zil-uh-] / ɔgˈzɪl jə ri, -ˈzɪl ə- /

adjective

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.

   Synonyms:

   secondary, ancillary, backup

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.

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noun

auxiliaries plural

1. a person or thing that gives aid of any kind; helper.

   Synonyms:

   help, assistant, ally, aide

2. an organization allied with, but subsidiary to, a main body of restricted membership, especially one composed of members' relatives.

   The men's club and the ladies' auxiliary were merged into one organization.

3. 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. Nautical. a sailing vessel carrying an auxiliary propulsion engine or engines.

auxiliary British  

/ -ˈzɪlə-, ɔːɡˈzɪljərɪ /

adjective

1. secondary or supplementary

2. supporting

3. nautical (of a sailing vessel) having an engine

   an auxiliary sloop

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noun

1. a person or thing that supports or supplements; subordinate or assistant

2. nautical

   1. a sailing vessel with an engine

   2. the engine of such a vessel

3. navy a vessel such as a tug, hospital ship, etc, not used for combat

Other Word Forms

Noun Inflected Forms

• auxiliaries
  plural

Etymology

Origin of auxiliary

1595–1605; < Latin auxiliārius assisting, aiding, helping, equivalent to auxili ( um ) aid, help ( aux ( us ) increased, augmented (past participle of augēre: aug- increase + -sus, variant of -tus past participle suffix) + -ilium noun suffix) + -ārius -ary

Explanation

When you're offering something in support of an already existing thing, you're offering something auxiliary. The auxiliary police will help out the regular police with things like directing traffic and crowd control when there's a special event in town. The Latin word auxilium means "help," and so auxiliary means something that "helps" by providing backup or support. Think of auxiliary verbs (sometimes called helper verbs), that provide support within a verb phrase, as "is" does in "Helen is playing." You can have an auxiliary engine in a car, an auxiliary cook at a restaurant, an auxiliary electrical network at a factory, or auxiliary troops standing by during battle. A "Ladies Auxiliary" functions as support for institutions such as churches, synagogues, or charities.

Example Sentences

See Examples For:

auxiliary auxiliaries

A cousin who happened to be an auxiliary police officer was let onto the scene.

From Slate ● Jul. 7, 2026

Using auxiliary degrees of freedom is not a new concept in physics.

From Science Daily ● Jun. 16, 2026

The safety concern is that, during an outage, this auxiliary electricity source could endanger electricians or utility workers.

From The Wall Street Journal ● Jun. 5, 2026

The Congolese army sometimes uses Codeco as an auxiliary force.

From Barron's ● May 9, 2026

Livermore seemed to be an auxiliary outpost caught between two larger labs, Los Alamos and Berkeley, and it was hardly unreasonable to wonder, with Rabi, if it would ever amount to more.

From "Big Science" by Michael Hiltzik

“We tend to undervalue and I would say underinvest in those unsexy but important capabilities like the oilers, like the auxiliaries, like the tenders. It’s the quiet backbone of American naval power.”

From The Wall Street Journal ● Apr. 10, 2026

Back then, California’s educational poobahs saw computers and typing as auxiliaries to learning instead of the essential skills we view them as today.

From Los Angeles Times ● Jan. 11, 2024

The group, made up of 3,530 people - 2,180 combatants and 1,350 auxiliaries - has maintained a bilateral ceasefire with the Colombian government since the beginning of the year.

From Reuters ● Apr. 16, 2023

Plato’s notion of three tiers of society—guardians, auxiliaries, and laborers—corresponds with elements of the soul.

From Textbooks ● Jun. 15, 2022

This cartoon explains a traditional rule about two common modal auxiliaries: At least Mrs. O’Malley didn’t give the standard grown-up’s answer to a child’s request with cart: “You can, but the question is, may you?”

From "The Sense of Style" by Steven Pinker

Related Words

• ancillary