auxiliary

UK: /ɔːgˈzɪljəri/

US: /ɔgˈzɪljəri, -ˈzɪlə-/

US: (ôg zil′yə rē, -zil′ə-)

Inflections of 'auxiliary' (n): npl: auxiliaries

WordReference Random House Learner's Dictionary of American English © 2026

aux•il•ia•ry /ɔgˈzɪlyəri, -ˈzɪlə-/   adj., n., pl. -ries. 
adj. 

1. additional;
   secondary;
   used as a substitute or reserve when needed:
   an auxiliary power station.
2. giving support;
   serving as an aid:
   They served in an auxiliary capacity.

n. [countable]

3. a person or thing that gives aid;
   helper.
4. an auxiliary organization:
   The women's auxiliary raised money for the school.
5. Grammar auxiliary verb.

WordReference Random House Unabridged Dictionary of American English © 2026

aux•il•ia•ry  (ôg zil′yə rē, -zil′ə-), adj., n., pl. -ries. 
adj. 

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.
3. Nautical, Naval Terms (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.

n. 

5. a person or thing that gives aid of any kind;
   helper.
6. an organization allied with, but subsidiary to, a main body of restricted membership, esp. one composed of members' relatives:
   The men's club and the ladies' auxiliary were merged into one organization.
7. Grammar See auxiliary verb. 
8. Military auxiliaries, foreign troops in the service of a nation at war.
9. Military [Navy.] a naval vessel designed for other than combat purposes, as a tug, supply ship, or transport.
10. Nautical a sailing vessel carrying an auxiliary propulsion engine or engines.

• 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, nominal suffix) + -ārius -ary
• 1595–1605

Synonyms

• 2. backup, ancillary, secondary.
• 5. aide, ally, assistant; help.

Collins Concise English Dictionary © HarperCollins Publishers::

auxiliary / ɔːɡˈzɪljərɪ -ˈzɪlə-/ adjective

1. secondary or supplementary
2. supporting

noun ( -ries)

1. a person or thing that supports or supplements; subordinate or assistant
2. a sailing vessel with an engine
3. the engine of such a vessel

Etymology: 17th Century: from Latin auxiliārius bringing aid, from auxilium help, from augēre to increase, enlarge, strengthen