auxiliary

[1]	help , assistance , aid , support , accessory
[2]	helper , assistant , aide , alter ego , supporter , (Colloq) man Friday , girl Friday

adj.

[1]	helping , assisting , supportive , aiding , abetting , helpful , accessory , supplementary
[2]	subordinate , additional , supplemental , subsidiary , secondary , ancillary , extra , reserve , accessory
[3]	adjunct , adjuvant , appurtenant