wanse (third-person singular simple present wanses, present participle wansing, simple past and past participle wansed)
From Middle English wansen (“to decrease, diminish”), from Old English wansian (“to diminish”), from Proto-Germanic *wansōną, *wanisōną (“to lessen”), from Proto-Indo-European *(e)wAn-, *wān- (“empty”). Cognate with Old Norse vansa (“to do too little”), Old Norse vansi (“lack, want”). More at wane.