Definition of rotor in English:


Syllabification: ro·tor
Pronunciation: /ˈrōtər


  • 1A rotary part of a machine or vehicle, in particular.
    More example sentences
    • As a message was typed into the machine, these rotors would spin around and calculate a letter to substitute for each letter of the message.
    • This lessens the wear on brake drums, rotors and pads.
    • Enigma allowed an operator to type in a message, then scramble it by means of three to five notched wheels, or rotors, which displayed different letters of the alphabet.
  • 1.1A hub with a number of radiating airfoils that is rotated in an approximately horizontal plane to provide the lift for a rotary-wing aircraft.
    More example sentences
    • The aircraft featured two large rotors located in nacelles on the ends of its wings linked to an air-cooled Daimler Benz 600 engine in the fuselage.
    • The aircraft would have launched standing upright like a rocket, but instead of using a blast of fire to take off the pilot would have simply adjusted the thrust and pitch of the rotors as with a helicopter.
    • The sound of the helicopter's rumbling rotors became louder, as it flew by directly overhead us, and began hovering over the red smoke.
  • 1.2The rotating assembly in a turbine, especially a wind turbine.
    More example sentences
    • Should they malfunction or prove insufficient to slow the rotor in high winds, a large disk brake mounted on the generator shaft can smoothly bring the turbine to a halt.
    • The higher-wattage plants, with their large-diameter, low-rotation-per-minute rotors, are designed to capture energy from low wind speeds.
    • Take away the 2.2 birds killed by the rotors, and the balance for wind energy, + 1707.8 birds per turbine a year, is not bad.
  • 1.3The armature of an electric motor.
  • 1.4The rotating part of the distributor of an internal combustion engine that successively makes and breaks electrical contacts so that each spark plug fires in turn.
    More example sentences
    • Motorists who failed to immobilise their cars, by taking away the rotor arm from the distributor, were liable to find their tyres deflated by the police.
    • I immediately changed the oil, plugs, distributor cap, rotor arm, and a friendly independent specialist fixed the exhaust.
    • After 20 minutes he decided the problem was with the rotor arm, and fashioned some wire underneath it to solve the problem.
  • 1.5The rotating container in a centrifuge.
    More example sentences
    • One junior intelligence analyst thought that although they weren't at all like modern American centrifuge rotors, they might be usable in what are known as a Zippe centrifuge.
    • The Department of Energy rejected the claim that the country was importing aluminum tubes to produce centrifuge rotors for enriching uranium.
  • 1.6The rotary winder of a clockwork watch.
  • 1.7 Meteorology A large eddy in which the air circulates around a horizontal axis, especially in the lee of a mountain.


early 20th century: formed irregularly from rotator.

More definitions of rotor

Definition of rotor in:

Get more from Oxford Dictionaries

Subscribe to remove adverts and access premium resources

Word of the day maelstrom
Pronunciation: ˈmeɪlstrəm
a powerful whirlpool in the sea