ad·junct
A thing added to something else as a supplementary rather than an essential part.
Adjective
Connected or added to something, typically in an auxiliary way: "alternative or adjunct therapies".
Synonyms
noun: supplement - addition - appendage - annex
adjective: subsidiary - ancillary - accessory
Source: Google Dictionary
noun: supplement - addition - appendage - annex
adjective: subsidiary - ancillary - accessory
Source: Google Dictionary