auxillary
/ˌɒksɪˈlɛəri/ or /ˌɔːɡzɪˈlɛri/Definitions
1. adjective
serving to support or supplement something, especially a military force
“The auxiliary troops provided crucial backup during the battle.”
2. noun
a person or thing that provides support or assistance
“The auxiliary officer helped the main officer with the navigation system.”
3. verb
to provide support or assistance, especially to a military force
“The country decided to auxiliary the UN peacekeeping mission.”