Adjectives are traditionally defined as words that describe nouns. For example, the adjectives gray, sleepy, and red describe the nouns puppy, girl, and barn in the sentences the gray puppy barked, the girl is sleepy, and the farmer painted the barn red. For more information on adjectives, please read the article Adjectives – The Qualifiers that Add Emphasis to Your Words.
Prototypical adjectives perform four grammatical functions in English: adjective phrase head, noun phrase modifier, subject complement, and object complement. For example, the adjective large functions as the head of the adjective phrase quite very large. The adjective angry likewise functions as a noun phrase modifier in the angry man, tall as a subject complement in your son is tall, and guilty as an object complement in the jury found the defendant guilty.
Prototypical adjectives also express degrees of modification. Adjectives in English can express three degrees: positive, comparative, superlative. Positive forms of adjectives are identical to the dictionary form as in smart and intelligent. Comparative forms take the suffix -er or the adverb more to compare two "things" as in smarter and more intelligent. Superlative forms that the suffix -est or the adverb most to compare more than two "things" as in smartest and most intelligent.
Prototypical adjectives can also be used attributively, postpositively, and predicatively. Adjectives used attributively immediately precede the modified noun as in purple in purple crayon. Adjectives used postpositively directly follow the modified noun as in elect in president elect. Adjectives used predicatively appear in the predicate as in wimpy in the boss is wimpy and plaid in the child colored the house plaid. The function of noun phrase modifier can be either attributive or postpositive while both the functions of subject complement and object complement are predicative.