Proper adjective

Proper adjectives are special adjectives that are made from proper nouns. A proper noun is a type of noun that names a specific person, place, or thing, such as a person's name (like Jackie or Brian), the name of a city (like Seattle or Chicago), or the name of a brand (like Nike or Apple).

A proper adjective is made from a proper noun. For example, the proper noun Seattle would have the proper adjective Seattleite, and the proper noun Apple would have the proper adjective Appleian.

So when you use a proper adjective, you're saying something like "Jackie-ish" or "Apple-ish" to describe something else. It's a way of saying that something is like a specific thing or person.