(often + to/of) something added or joined to another thing as an incidental accompaniment rather than an essential part

Hitherto galleries had been living-rooms presenting pictures as adjuncts to polite living — Daily Telegraph

in grammar, a word or group of words, e.g. an adverb or prepositional phrase, that is not one of the principal structural elements in a sentence

a person, usu in a subordinate or temporary capacity, assisting another to perform some duty or service

Walpole was a minister given by the King to the people: Pitt was a minister given by the people to the King, – as an adjunct — Dr Johnson