Old English wanian "make or become smaller gradually, diminish, decline, fade," from Proto-Germanic *wanen (cognates: Old Saxon wanon, Old Norse vana, Old Frisian wania, Middle Dutch waenen, Old High German wanon "to wane, to grow less"), from *wano- "lacking," from PIE *we-no-, from root *eue- "to leave, abandon, give out" (see vain). Related: Waned; waning; wanes.