Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Adjectives
Parts of speech
Grammar Basics

An adjective is a word used to modify, or describe, a noun or pronoun. An adjective usually answers one of these questions: Which one? What kind? How many?

Adjectives usually come before the words they modify. They may also follow linking verbs, in which case they describe the subject. (See 48b.)

The definite article the and the indefinite articles a and an are also classified as adjectives.

Some possessive, demonstrative, and indefinite pronouns can function as adjectives: their, its, this, all (see 47b). And nouns can function as adjectives when they modify other nouns: apple pie (the noun apple modifies the noun pie; see 47a).

TIP: You can find more details about using adjectives in 26. If you are a multilingual writer, you may find help with articles and specific uses of adjectives in 29, 30f, and 30g.