Source : Webster's Revised Unabridged Dictionary (1913)

Rotor \Ro"tor\, n. (Elec.)
   The rotating part of a generator or motor.

Source : WordNet®

rotor
     n 1: the rotating armature of a motor or generator [syn: {rotor
          coil}] [ant: {stator}]
     2: the revolving bar of a distributor
     3: rotating mechanism consisting of an assembly of rotating
        airfoils; horizontal rotors on a helicopter or compressor
        rotors of a jet engine