The proper noun for a person from Scotland is "Scot."
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.
The proper noun would be Switzerland.
Scottish is the proper adjective for Scotland.
The proper adjective for Wales is Welsh.
The proper noun for a person from Scotland is "Scot."
Scottish or Scots can be used to describe something of or from Scotland. Scotch can be used to refer to food and drink of or from Scotland.
The phrase "he was Scottish" is a sentence that consists of a subject ("he") and a predicate adjective ("Scottish"). In this case, "Scottish" acts as an adjective describing the subject "he."
The proper adjective for Portuguese is "Portuguese."
The proper adjective for southwest is "southwestern."
The proper adjective for Haiti is Haitian.
Vietnamese is the proper adjective for Vietnam.
The proper adjective for Siam is Siamese.
The proper adjective for Georgia is Georgian.
The proper adjective for Mayan is "Mayan."