IRANIAN is the appropriate national descriptor. However, many Iranians prefer to be called Persians, especially if they live outside of Iran and do not identify with the current regime.
The proper adjective for the noun Afghanistan is Afghan.
Example: My dog is an Afghan hound.
The noun Afghanistan is a proper noun, the name of a specific country. The common noun is country.
Irani
Iranian.
Vietnamese is the proper adjective for Vietnam.
The proper adjective for the proper noun 'Celt' is Celtic.Please note that a proper noun and a proper adjective is always capitalized.
Ghanian is the proper adjective for Ghana.
Since spice isn't a proper noun, it can't have a proper adjective. The adjective of spice is spicy.
Since writer is not a proper noun, it doesn't have a proper adjective.
The proper noun for the proper adjective Iranian is Iran, once ancient Persia.The word Iranian is also a proper noun, a word for a native or national of Iran, or a person of Iranian descent.
The proper adjective for Haiti is Haitian.
The proper adjective for southwest is "southwestern."
The proper adjective for Portuguese is "Portuguese."
Someone from Israel is called an "Israeli".
Vietnamese is the proper adjective for Vietnam.
The proper adjective for Siam is Siamese.
The proper adjective for George is Georgian.
Freudian is the proper adjective for Freud.
The proper adjective for Georgia is Georgian.
The proper adjective for Mayan is "Mayan."
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.