Rotor may refer to:

  • A rotating part of a mechanical device, for example in an electric motor, generator, alternator or pump.

In engineering:

  • Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element called the stator.
  • Helicopter rotor, the rotary wing(s) of a rotorcraft such as a helicopter
  • 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 (crank), a variable-angle bicycle crank
  • Rotor (brake), the disc of a disc brake, in U.S. terminology
  • Rotor (brake mechanism), a device that allows the handlebars and fork to revolve indefinitely without tangling the rear brake cable
  • Rotor (distributor), a component of the ignition system of an internal combustion engine
  • Rotor (engine), the powered part of a pistonless rotary engine
  • Rotor (antenna), an electric motor that rotates an antenna to the direction of transmission or reception

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 mathematics:

  • Rotor (mathematics), an n-blade object in geometric algebra, which rotates another n-blade object about a fixed or translated point
  • Curl (mathematics), known as rotor in some countries, a vector operator that shows a vector field's rate of rotation

In medicine:

  • Rotor syndrome, a rare liver disorder

In biology and chemistry:

  • The rotating part of a centrifuge, which also holds the samples

In other fields:

  • SC Rotor Volgograd, a Russian football club
  • Rotor (Sonic the Hedgehog), a fictional character from the Sonic the Hedgehog universe
  • Rotor (ride), the trade name for an amusement ride
  • Rotor (meteorology), a turbulent horizontal vortex that forms in the trough of lee waves
  • Rotor, a space colony in Isaac Asimov's novel Nemesis
  • R.O.T.O.R., a 1989 science fiction/action movie
  • Vibrator (sex toy), a Japanese usage of similar sounds in English. Also spelt as rotar.