A Military Writer's Handbook
Primer - The Parts of Speech

Adjectives

An adjective is a word that describes or adds to the meaning of a noun or pronoun. Adjectives in English usually appear before the noun. When proper nouns are used as adjectives, they are spelled with a capital letter; numbers can function as adjectives; and adjectives can also follow the to be verb.

Types of Adjectives

Proper nouns as adjectives
When proper nouns are used as adjectives they are spelled with a capital letter:

Canada's forces
French troops

Numbers as adjectives
Numbers can function as adjectives when they help define a noun:

The seven soldiers entered the ravine.

Adjectives and the to be verb
Adjectives can follow the to be verb; to discover the simple construction of noun and adjective, simply turn the sentence around:

The drill sergeant is enthusiastic (the enthusiastic drill sergeant)

The lunch special might be unappetizing (the unappetizing lunch)

Articles and pronouns as adjectives
Articles and some pronouns (those that imply possession) are considered adjectives when they appear before a noun to identify or to describe it in some way.

my boots
that vehicle
Whose sword is this?