- a rotating member of a machine.
- a system of rotating airfoils, as the horizontal ones of a helicopter or of the compressor of a jet engine.
- any of a number of tall, cylindrical devices mounted on a special ship (rotor ship ) and rotated in such a way that the Magnus effect of wind impinging on the cylinders is used to drive and maneuver the vessel.
- (in a self-winding watch) a weight eccentrically mounted on an arbor for keeping the mainspring wound.
- the rotating member of a machine or device, esp the armature of a motor or generator or the rotating assembly of a turbine
- a device having blades radiating from a central hub that is rotated to produce thrust to lift and propel a helicopter
- the revolving arm of the distributor of an internal-combustion engine
- a violent rolling wave of air occurring in the lee of a mountain or hill, in which the air rotates about a horizontal axis
