1550s, "to cut thin shavings from (something) with a knife," from Middle English whittel "a knife," especially a large one (c.1400), variant of thwittle (late 14c.), from Old English þwitan "to cut," from Proto-Germanic *thwit- (cognates: Old Norse þveita "to hew"), from PIE root *twei- "to agitate, shake, toss." Figurative sense is attested from 1746. Related: Whittled; whittling.