A Student's Introduction to English Grammar

Although adjectives typically denote properties, that’s not definitive. The distinctive properties of prototypical adjectives are gradability inflection for comparative and superlative. Adjective phrases (AdjPs) function as predicative complements and modifiers in nominals, though some specialize in one of these. AdjPs take adverbs, notably ‘very’, as modifiers. These properties generally distinguish them from nouns and verbs which can be useful in fused modifier-heads or with overlap, as in ‘it’s flat’ vs ‘I have a flat’. AdjPs differ from DPs in always being omissible from an NP, while a DP in determiner function is often required. Also DPs, but not AdjP can occur in as a fused head in a partitive construction. AdjPs also occur as supplements, here differing from PPs in that AdjPs typically have a predicand that is the subject of the main clause. Like most other phrases, AdjPs allow complements, usually PPs or subordinate clauses.

The adverb category is the most heterogenous in the properties of its members. Many adverbs are formed from adjectives using the ‘⋅ly’ suffix, but AdvPs don’t function as attributive modifiers in nominals and rarely function as or allow complements.