Adjectival Phrase

The term adjectival phrase, adjective phrase, or sometimes phrasal adjective may refer to any one of several types of grammatical phrase.

1. In syntax, the term adjectival phrase or adjective phrase refers to a phrase built upon an adjective, which functions as the head of that phrase. For example, the phrase much quicker than I is based on the adjective 'quick', and the phrase fond of animals is based on the adjective 'fond'. Such phrases may be used predicatively, as in They are much quicker than I (≈ they are quick) or they are fond of animals (≈ they are fond). When used attributively within a noun phrase, complex adjectival phrases tend to occur after the noun: I found a typist much quicker than I (compare I found a quick typist, where a simple adjective occurs before the noun). The words modifying the head adjective may be adverbs (much quicker, very pretty), prepositional phrases (fond of animals, happy about the news), or subordinate clauses (happy that you came).
2. A different use of the term is for a phrase that modifies a noun as an adjective would, even if it does not contain or is not based on an adjective. These may be more precisely distinguished as phrasal noun modifiers. For example, in Mr Clinton is a man of wealth, the prepositional phrase of wealth modifies a man the way an adjective would, and it could be reworded with an adjective as Mr Clinton is a wealthy man. Similarly, that boy is friendless (an adjective friendless modifies the noun boy) and that boy is without a friend (a prepositional phrase without a friend modifies boy).
3. Under some definitions the term adjectival phrase is only used for phrases in attributive position, within the noun phrase they modify. These may be more precisely distinguished as phrasal attributives or attributive phrases. This definition is commonly used in English style guides for writing, because attributive phrases are typically hyphenated, whereas predicative phrases generally are not, despite both modifying a noun. Compare a light-blue purse and a purse which is light blue; without the hyphen, a light blue purse would be read as a light purse which is blue – that is, without 'light blue' being understood as a unit. Only a light-blue purse would be considered to contain an adjectival phrase under this definition, although under the syntactic definition a purse which is light blue contains an adjectival phrase as well.

Although the purse example is based on an actual adjective, this is not generally the case: an on-again-off-again relationship contains no adjectives, for example, and so is not an adjectival phrase under the syntactic definition.