* When referring to something precise, specific or appropriate, it's a formal adjective.
Examples:
- Proper nouns: names of people, places, and organizations.
- Proper use: "The CEO will give the proper instructions for this assignment".
* When referring to someone's behavior or actions, in an informal way, it's not considered formal.
Examples:
- Doing the right thing: behaving in a morally correct way.
- Proper guy: cool, handsome, attractive (informal).
In summary, "proper" can be a formal adjective when referring to something specific or precise, but it's not considered formal when describing someone's behavior or actions in a casual way.