etesian

Etymology according to A.W.A.D.: "The word refers to the annual summer winds of the Mediterranean. It's derived from Latin etesius, from Greek etesios, from etos (year). Ultimately from the Indo-European root wet- (year) that is also the source of such words as veteran, veal (in the sense of yearling), and veterinary (relating to the beasts of burden, perhaps alluding to old cattle), inveterate, wether, and bellwether."

etesian a periodic, seasonal word