auxiliary

/ɔɡˈzɪljəri/
/ɔɡˈzɪl(ə)ri/

adjective

Providing supplementary or additional help and support.

auxiliary airport staff

additional,supplementary,supplemental,extra,reserve,backup,emergency,fallback,spare,substitute,other

noun

A person or thing providing supplementary or additional help and support.

a nursing auxiliary

assistant,helper,aide