In grammar, an adverbial (abbreviated adv) is a word (an adverb) or a group of words (an adverbial clause or adverbial phrase) that modifies or more closely defines the sentence or the verb. (The word adverbial itself is also used as an adjective, meaning "having the same function as an adverb".) Look at the examples below:
Adverbials most commonly take the form of adverbs, adverb phrases, temporal noun phrases or prepositional phrases. Many types of adverbials (for instance: reason and condition) are often expressed by clauses.
An adverbial is a construction which modifies or describes verbs. When an adverbial modifies a verb, it changes the meaning of that verb. Word groups, which are also considered to be adverbials, can also modify verbs: for example, a prepositional phrase, a noun phrase, a finite clause or a non-finite clause. Prepositional phrase in a sentence may be adverbial; that is, it modifies a verb.
Adverbials are typically divided into four classes:
Adverbial complements (i.e. obligatory adverbial) are adverbials that render a sentence ungrammatical and meaningless if removed.
Adjuncts: These are part of the core meaning of the sentence, but if omitted still leave a meaningful sentence.
Conjuncts: These link two sentences together.
Disjuncts: These make comments on the meaning of the rest of the sentence.
All verb- or sentence-modifying adjuncts are adverbials, but some adverbials are not adjuncts.
Prepositions (in, out, etc.) may be used adverbially to indicate direction or location.
In some models of grammar negators such as "not" and "never" are considered adverbs and their function that of negating adverbial.