From Middle English whittel (“large knife”), an alteration of thwitel, itself from thwiten (“to whittle”), from Old English þwītan (“to strike down, whittle”), from Proto-Germanic *þwītaną, possibly from Proto-Indo-European *twey- (“to shake, hurl, toss”). Compare Old Norse þveita (“to hurl”), Ancient Greek σείω (seíō, “I shake”). Related to thwite and thwaite.