Rotor (rotating part) may mean:
In engineering:
- Helicopter rotor, the rotary wing(s) of a rotorcraft such as a helicopter
- Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element called the stator.
- ROTOR, a former radar project in the UK following the Second World War
- Rotor (turbine), the rotor of a turbine powered by fluid pressure
- Rotor (brake), the disc of a disc brake, in U.S. terminology
- Rotor (distributor), a component of the ignition system of an internal combustion engine
- Rotor (engine), the rotary piston in a rotary combustion engine
- Rotor (antenna), an electric motor that rotates an antenna to the direction of transmission or reception
- Rotor (magazine), a US magazine covering the civil helicopter industry
In computing:
- Rotor machine, the rotating wheels used in certain cipher machines, such as the German Enigma machine
- Rotor (software project), the former code name for Microsoft's shared source implementation of its Common Language Infrastructure
In music:
- Rotor (band), a German progressive stoner rock band
- Rotor Plus (sometimes known as Rotor), an experimental electronica band from New Zealand
In other fields:
