c. 1200, "to depart, go make off; turn away or aside;" c. 1300, "to turn aside, deviate from a straight course;" in form from Old English sweorfan "to rub, scour, file away, grind away," but sense development is difficult to trace. The Old English word is from Proto-Germanic *swerb- (cf Old Norse sverfa "to scour, file," Old Saxon swebran "to wipe off"), from PIE root *swerbh- "to turn; wipe off." Cognate words in other Germanic languages (Old Frisian swerva "to creep," Middle Dutch swerven "to rove, roam, stray") suggests the sense of "go off, turn aside" might have existed in Old English, though unrecorded. Related: Swerved; swerving.