auxiliary
adjective
uk/ɔːɡˈzɪliəri/ usused in addition to the main team, organization, system, etc. in order to give extra help and support:
auxiliary staff/police/nurses About 4800 unarmed auxiliary police officers work on a volunteer basis with the New York Police Department.
auxiliary
noun [ C ]
WORKPLACE uk/ɔːɡˈzɪliəri/ usan employee, volunteer (= someone who works without pay), or organization whose job is to give extra help or support:
hospital auxiliaries