verbStrong class 2to fly or whirl aboutto fume; smoke; smolderTraditionally derived from Proto-Indo-European *dʰewbʰ- (‘to whisk, smoke, obscure’), which may be an extension of Proto-Indo-European *dʰewh₂- (‘to whirl, waft, stink, shake; steam, haze, smoke’), and compared with Ancient Greek τῡ́φω (tū́phō, ‘to smoke’) (though Orel is skeptical of this derivation). Other theories include derivation from a Proto-Indo-European *stewbʰ- (‘to drive about’), and comparison with Ancient Greek στυφελίζω (stuphelízō, ‘to strike hard, dash, beat, drive away’).However, Kroonen prefers to derive the word from a Proto-Indo-European *tsewbʰ- (‘to fly about’), with the same metathesis from Proto-Indo-European to Proto-Germanic as seen in *stelaną (‘to steal’), and compares Lithuanian siaũbti (‘to dash about’).