Well there is good, or bad, or long, or short...All of these can describe a year. If you mean how often something happens, like a carnival every year, yearly is ok, but most prefer annually.
sagger new year's
The proper adjective for southwest is "southwestern."
The proper adjective is Haitian.
The proper adjective for Portuguese is "Portuguese."
Some adjectives that could describe a year are: bad good hot cold dry wet interesting leap dull productive unproductive
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 Georgia is Georgian.
The proper adjective for George is Georgian.
Freudian is the proper adjective for Freud.
Mayan is itself a proper adjective.
The proper adjective for Siam is Siamese.