The following tree diagram in the style of The Cambridge Grammar of the English Language shows the AdjP very happy to try, with the adverb very as a modifier and the clause to try as a complement.
Finite clause complements can be declarative (e.g., very pleased that I had bought his book) or interrogative (e.g., not sure whether I want to keep reading).
[a] A small number of adjectives (due, like, near, unlike, and worth) can take noun phrases as complements.
[9] At the clause level, adjective phrases commonly appear as predicative complements.
Predicative complements may be subject-related, as in the previous example, or object-related, the latter being licensed by complex transitive verbs such as feel and make, as in That made her hungry, where the property of being hungry is ascribed to the syntactic object and semantic predicand, her.
In cases such as the very poor and the French which denote a class, traditional grammars see the adjective as being "used as a noun".
Other grammars see this as a case of ellipsis, where the head noun is simply left out and the AdjP is a regular modifier.
Other accounts, such as one advanced by Bas Aarts, do not assume ellipsis but instead argue that phrases like these are best analyzed as noun phrases with an empty element functioning as the head, yielding an analysis like this: [NP the [AP veryAdv poorAdj] ∅N].
[16] The Cambridge Grammar of the English Language takes such instances to be fused modifier-heads.
[20] Linguist and historian Peter Matthews observes "that the attributive and predicative uses of adjectives have diverged" and continue to do so.
What these words have in common is, to put it in traditional terms, that they "qualify" nouns.
Words like many and few, along with numbers (e.g., many good people, two times) are traditionally categorized as adjectives, where modern grammars see them as determiners.
This type includes words that "qualify" a noun and must agree with it in number: all, these, some, no, etc.
[18] Some of these are categorized by modern grammars as adjectives (e.g., Italian, Christian, Dubliner, Chinese, Thatcherite, etc.)
[18] This type includes which and whose (e.g., the person whose book I bought) appearing in relative constructions.
Adjectives with two syllables vary in whether they can mark degree of comparison through inflectional suffixes or must do so periphrastically with more and most.
Adjectives may be formed by the addition of affixes to a base from another category of words.
Through a process of derivational morphology, adjectives may form words of other categories.
Typically, adjectives and nouns in English can be distinguished by their morphological and syntactic features.
[28] The following table summarizes these characteristics: The distinction between adjective and noun in English is not as clear in certain cases, such as with colour terms and noun-like words occurring in attributive position.
However, the categorization of colour terms is less clear in cases like The foliage emerged, becoming deep green as the summer unfolds.
Here, the modifier of the colour term is an adjective (deep) rather than an adverb (deeply), which suggests that green is a noun.
But the phrase occurs as the predicative complement of become and could, in principle, be modified by an adverb like very or appear in comparative form, which are typical characteristics of adjectives.
[29] Bas Aarts notes that this apparent dual categorization can be avoided by treating terms like deep orange as adjective-adjective compounds.
[16] Almost any noun may appear in attributive position (e.g., a geography student), but in doing so they have traditionally said to be "functioning as an adjective".
Such words are like adjectives in that they function as pre-head modifiers of nouns and resist pluralization in this position (*a geographies student).
These can often be distinguished from verbs by their ability to be modified by very (e.g., very tired but not *very based on it) or appear after become as predicative complements.
The adjectives wrong and right are often incompatible with an indefinite NP (e.g., *they found a right person; here suitable would be better) but are possible in other cases (e.g., there isn't a right answer).
Unlike some languages, English does not mark the specificity of NPs grammatically.
Similarly, a bigmouth is not a mouth that is big, nor is a highway a way that is high or software ware that is soft.