ancillary
Pronunciation: /anˈsɪləri/
adjective
noun ( plural ancillaries)
- a person whose work provides necessary support to the primary activities of an organization, system, etc.: the employment of specialist teachers and ancillaries
- something which functions in a supplementary or supporting role: undergraduate courses of three main subjects with related ancillaries the system measures engine power at the flywheel with all ancillaries (fan, standard exhaust, etc.) connected

Origin:
mid 17th century: from Latin ancillaris, from ancilla 'maidservant'