Proper Adjective Definition
A proper adjective is an adjective that is written with a capital letter. They are often derived from proper nouns:
A Japanese camera- Japanese is derived from the proper noun Japan.
This is not always the case:
Native Americans- Native is not derived from a proper noun, but is capitalised as the words together form the name of the group of people.
Ordinary adjectives that are not written with a capital letter are common adjectives.