No, Egyptian is an adjective used to describe something of or from Egypt (a proper noun). Although Egyptian is an adjective, it is still capitalized.
Egyptian is the proper adjective for Egypt.
The word Egyptian is a proper noun as a word for a person of or from the country of Egypt. The word Egyptian is also a proper adjective that describes a noun as of or from the country of Egypt.
The proper adjective for southwest is "southwestern."
The proper adjective is Haitian.
The proper adjective for Portuguese is "Portuguese."
Vietnamese is the proper adjective for Vietnam.
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 George is Georgian.
The proper adjective for Siam is Siamese.
Mayan is itself a proper adjective.
Freudian is the proper adjective for Freud.