1307, from frequentative form of stem of O.E. verb swifan "to move in a course, sweep" (a class I strong verb), from P.Gmc. *swipanan (cf. O.Fris. swiva "to be uncertain," O.N. svifa "to rove, ramble, drift"), from PIE base *swei- "swing, bend, move in a sweeping manner." M.E. swive was the principal slang for "to have sexual intercourse with," a sense that developed c.1300. This probably explains why, though the root is verbal, the verb swivel is not attested in Mod.Eng. until 1794.