It was defective. We saw several Corvettes race by. Most adjectives, like red in the above example, are used to describe. This year's attendance was smaller than last year's. This year's attendance was the smallest in ten years.
Many pronouns can function as adjectives when they are followed by a noun.
Proper adjectives are capitalized. One of the most common adverbs is not. Giles and Rebecca recently visited Atlanta. They had an unexpectedly exciting trip. Frankly, they would have liked to stay another month.