Danish
The proper adjective for Copenhagen is "Copenhagenish."
Since brass isn't a proper noun, it can't have a proper adjective. The adjective of brass is brassy.
To change "France" from a proper adjective to a proper noun, you can refer to France as a specific place, country, or entity instead of using it to describe something. For example, instead of saying "French culture," you can say "France's culture," making "France" the proper noun.
Scotland!
Switzerland is the proper noun.
The proper adjective for southwest is "southwestern."
The proper adjective is Haitian.
The proper adjective for Portuguese is "Portuguese."
Denmarks best midfielder is Ramadhal.
Vietnamese is the proper adjective for Vietnam.
The proper adjective for Georgia is Georgian.
The proper adjective for George is Georgian.
Freudian is the proper adjective for Freud.
Mayan is itself a proper adjective.
The proper adjective for Siam is Siamese.
No, old is not a proper adjective. A proper adjective is an adjective derived from a proper noun, such as Swiss cheese, Bolivian pottery, Chinese silk, etc.
The proper adjective for Antigua is Antiganantigan