Etymology
From Middle English wansen (“to decrease, diminish”), from Old English wansian (“to diminish”), from Proto-West Germanic *wansōn, a variant of *wanisōn, from Proto-Germanic *wanisōną (“to lessen”), from Proto-Indo-European *h₁weh₂- (“empty”). Cognate with Old Norse vansa (“to do too little, suffer loss”), Old Norse vansi (“lack, want”). More at wane.