The Collaborative International Dictionary of English v.0.48:

Rotor \Ro"tor\, n. (Elec.)
   The rotating part of a generator or motor. Contrasted with
   stator, the stationary part.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "rotor":
   airscrew, carousel, disk, driver, fan, impeller, merry-go-round,
   paddle wheel, piston, prop, propellant, propeller, propulsor,
   roller, rolling stone, rotator, roundabout, rundle, screw,
   screw propeller, top, turbine, twin screws, wheel, whirlabout,
   whirler, whirligig