An adverbial phrase is a grammatical structure within a sentence that expresses an adverbial idea and consists of one or more words. This type of phrase typically serves one of a number of different functions that provide more information about an action or description. Since this is a phrase, however, it does not contain both a subject and a verb, as that would be an adverbial clause and is a separate structure from other phrases. An adverbial phrase often serves the same purpose as an adverb in general, by modifying or describing a verb, adjective, or another adverb.
Also called an adverb phrase, an adverbial phrase is one of a number of different types of phrases that can make up a clause. A clause is a full expression of an idea, and complete sentences contain at least one clause that typically consists of a subject and predicate, or verb phrase. Within each clause are different phrases that consist of different words and serve different functions; an adverbial phrase functions by describing another phrase. This is similar in function to how an adverb by itself describes another verb, adjective, or adverb.
In the sentence “The cat ran quickly,” the word “quickly” is an adverb that describes the way in which the cat ran. An adverbial phrase serves much the same purpose, but does so with more words to express a more complex idea. “The cat jumped onto the table” is a single clause and is a complete sentence that consists of a subject and predicate. In this sentence, the subject is a noun phrase of “The cat,” which consists of the article “The” and the noun “cat.”
The predicate in this clause is a bit more complex, and consists of a verb phrase and an adverbial phrase. In this clause, the verb phrase consists only of the verb “jumped,” though a more complicated verb phrase could include an adverb such as “quickly jumped.” Since the two words are together without any additional words, the adverb is part of the verb phrase and not its own phrase.
The adverbial phrase in the full sentence, however, consists of a prepositional phrase, which itself is made up of a preposition and a noun phrase. “Onto” is the preposition in this sentence, and the noun phrase consists of the article “The” and the noun “table.” This phrase describes the action of the jump in greater detail.
Adverbial phrases can serve a number of purposes within a sentence, often depending on the form of the phrase itself. Phrases that include a prepositional phrase, such as the above example, are typically used to express manner, place, time, frequency, or purpose. Manner describes how something is done, place indicates where it is done, time shows when something occurs, frequency indicates how often it is done, and purpose demonstrates why something is done. “Onto the table,” for example, is used to illustrate the place where the cat jumped.