[ roh-ter ]
/ ˈroʊ tər /


Electricity. a rotating member of a machine.Compare stator(def 1).
Aeronautics. a system of rotating airfoils, as the horizontal ones of a helicopter or of the compressor of a jet engine.
any of a number of tall, cylindrical devices mounted on a special ship (rotor ship) and rotated in such a way that the Magnus effect of wind impinging on the cylinders is used to drive and maneuver the vessel.
(in a self-winding watch) a weight eccentrically mounted on an arbor for keeping the mainspring wound.

Nearby words

  1. rotisserie league baseball,
  2. rotl,
  3. roto,
  4. rotogravure,
  5. roton,
  6. rotor blade,
  7. rotor cloud,
  8. rotorcraft,
  9. rotorua,
  10. rotoscoliosis

Origin of rotor

First recorded in 1873; short for rotator Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for rotor

British Dictionary definitions for rotor


/ (ˈrəʊtə) /


the rotating member of a machine or device, esp the armature of a motor or generator or the rotating assembly of a turbineCompare stator
a device having blades radiating from a central hub that is rotated to produce thrust to lift and propel a helicopter
the revolving arm of the distributor of an internal-combustion engine
a violent rolling wave of air occurring in the lee of a mountain or hill, in which the air rotates about a horizontal axis

Word Origin for rotor

C20: shortened form of rotator

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for rotor



1873, irregular shortening of rotator (see rotate (v.)), originally in mathematics. Mechanical sense is attested from 1903; specifically of helicopters from 1930.

Online Etymology Dictionary, © 2010 Douglas Harper