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.
Egyptian is a proper adjective.
Athenian is a proper adjective for Athens.
Persian
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.
The word ancient is an adjective. It means very old.
No, "old" is not a proper noun. It is an adjective used to describe the age of a person, object, or thing.
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.
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.
The proper adjective for Georgia is Georgian.
The proper adjective for Antigua is Antiganantigan
Kuwaiti is the proper adjective for Kuwait.