ENGLISH
REFERENCE

auxiliary

adj. · n.
US //ɑɡˈzɪɫiɛɹi// UK //ɔːksˈɪliəɹi// aux·il·iary
  1. 1 providing extra help (adj.)
    C1 Advanced Formal

    giving extra help or support to a main person, group, or system.

    providing supplementary or additional help and support to a primary entity.

    Example

    The hospital hired auxiliary staff to help during the busy winter season.

    Example

    The main engine failed, but the auxiliary power unit kicked in immediately to keep the ship's navigation systems running.
  2. 2 held in reserve (adj.)
    C1 Advanced Technical

    kept ready to use if the main thing fails or if there is an emergency.

    functioning as a reserve or backup intended for use in exceptional circumstances.

    Example

    The building has an auxiliary water tank in case the city supply stops.

    Example

    Engineers designed an auxiliary cooling system to prevent a meltdown if the primary pumps were compromised.
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  1. 3 a helper or backup (n.)
    C1 Advanced Formal

    a person or thing that provides extra help, especially in the military or a large organization.

    an individual or group that acts in a supportive or subsidiary capacity, often within a military or medical hierarchy.

    Example

    She volunteered as a nurse's auxiliary at the local clinic.

    Example

    The army relied heavily on local auxiliaries to navigate the difficult mountain terrain during the campaign.
  2. 4 grammar (n.)
    B2 Upper Intermediate Technical

    a helping verb like 'be', 'do', or 'have' that is used with another verb.

    a verb used in forming the tenses, moods, and voices of other verbs.

    Example

    In the sentence 'I am eating', the word 'am' is an auxiliary.

    Example

    The student struggled to distinguish between the primary auxiliary and the main lexical verb in complex passive constructions.

    Usage

    Common auxiliaries in English include 'be', 'do', and 'have', as well as modal verbs like 'can' and 'must'.
    • helping verb
    • lexical verb
Origin

From Latin auxiliārius (“assistant, ally”), equiv. to auxiliāris (“helping, aiding”), from auxilium (“help, aid”), from augēre (“to increase”).

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