The proper adjective for southwest is "southwestern."
The proper adjective is Haitian.
The proper adjective for Portuguese is "Portuguese."
Yes, Vermont is a proper noun, the name of a state. A proper noun is the name of a person, place, thing, or a title; Vermont is the name of a place. Proper nouns are always capitalized.
Vietnamese is the proper adjective for Vietnam.
The proper adjective for George is Georgian.
Mayan is itself a proper adjective.
The proper adjective for Siam is Siamese.
The proper adjective for Georgia is Georgian.
Freudian is the proper adjective for Freud.
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