Origin and history of swerve

c. 1200, swerven, "depart, go make off; turn away or aside;" c. 1300, "turn aside, deviate from a straight course." In form it seems to be from Old English sweorfan "to rub, scour, file away, grind away," but sense development is difficult to trace, and "the sudden emergence of the sense of "turn aside" in ME. is remarkable" [OED 2nd ed. print, 1989].

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."

The development of senses appears to have been 'rub, wipe, polish, file, move to and fro, turn, turn aside, wander ' ; but two orig. diff. words may be concerned. [Century Dictionary]

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.

In reference to moral actions or courses by c. 1400. Transitive sense of "cause to change course" is from late 14c. The "filing" senses did not survive Old English but are preserved in swarf. Related: Swerved; swerving.

"a turning aside, a deviation from a course," 1741, from swerve (v.). Middle English had swerving (n.) "crookedness" (early 15c.).