Of or pertaining to an adverb; of the nature of an adverb; as, an adverbial phrase or form.

of or relating to or functioning as an adverb; "adverbial syntax"

a word group that is used as an adverb, or a word that isn't an adverb but is used as one

Functioning as an adverb. Phrases and clauses that modify verbs, adjectives, and other adverbs are adverbial.

A word or phrase which gives information about when, how, where, or in what circumstances something happens. It can be an adverb, a group of words with an adverb as a main word, or a prepositional phrase. E.g. They looked passionately at each other. She performed well at the Peninsula Hotel yesterday.

An adverbial is a word or expression in the sentence that functions as an adverb; that is, it tells you something about how the action in the verb was done.

In grammar an adverbial is a word (an adverb) or a group of words (an adverbial phrase or an adverbial clause) which modifies or tells us something about the sentence or the verb. The word adverbial is also used as an adjective, meaning 'having the same function as an adverb'.