The following is about the linguistics term; adjunct is also a term used in the brewing of beer.

In linguistics, an adjunct is a type of adverb illustrating the circumstances of the action. It expresses such relations as time, manner, place, frequency, reason and degree, i.e. it answers the questions: where, when, how and why. For example:

It's near Boston. (Place adjunct.)

He spoke calmly (manner adjunct), since he had all the time in the world (adjunct of reason).