Use adjectives to modify nouns or pronouns, to compare multiple nouns or to compound other adjectives. It is also possible to use adjectives de-nominally or adjectivally.
The most common form of an adjective is a description word that one uses before nouns to enhance or explain the noun. People use adjectives in other de-nominal ways, such as "mathematical" in the phrase "mathematical puzzle" or "metal" in the phrase "metal boat." Another use for adjectives is to put certain nouns into light by comparing the noun with another noun, such as "bigger" in the phrase "this house is bigger than this garage."