In linguistics, an adverbial phrase is a group of two or more words operating adverbially, meaning that their syntactic function is to modify a verb, an adjective, or an adverb. Adverbial phrases ("AdvP" in syntactic trees) are phrases that do the work of an adverb in a sentence.
Compare the following sentences:
- I'll go to bed soon.
- I'll go to bed in an hour.
- I'll go to bed when I've finished my book.
In the first, soon is an adverb (as distinct from a noun or verb), and it is an adverbial (as distinct from a subject or object). In the second sentence, in an hour has the same syntactic function, though it does not contain an adverb; therefore, a phrase consisting of a preposition and a noun (preceded by its article) can function as an adverbial and is called an adverbial phrase. In the third sentence, we see a whole clause functioning as an adverbial; it is termed an adverbial clause.
Like adverbs, complex adverbials can describe:
- Time (answers the question 'When?')
- She will be arriving in a short time.
- Place (answers the question Where?')
- She is waiting near the wall.
- Manner (answers the question 'How?')
- They are discussing the matter in a civilized way.
Adverbs modify the functional categories that occur in a sentence and may also be treated as predicates which are functionally open and require one or more arguments to be satisfied. It has been argued that the distribution of adverbs is largely conditioned by their lexical nature or thematic properties.