rotor

American  

[roh-ter] / ˈroʊ tər /

noun

1. Electricity. a rotating member of a machine.

2. Aeronautics. a system of rotating airfoils, as the horizontal ones of a helicopter or of the compressor of a jet engine.

3. 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.

4. (in a self-winding watch) a weight eccentrically mounted on an arbor for keeping the mainspring wound.

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rotor British  

/ ˈrəʊtə /

noun

1. the rotating member of a machine or device, esp the armature of a motor or generator or the rotating assembly of a turbine Compare stator

2. a device having blades radiating from a central hub that is rotated to produce thrust to lift and propel a helicopter

3. the revolving arm of the distributor of an internal-combustion engine

4. a violent rolling wave of air occurring in the lee of a mountain or hill, in which the air rotates about a horizontal axis

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Etymology

Origin of rotor

First recorded in 1873; short for rotator

Example Sentences

The spark plug ignites a fuel-air mix, causing the rotor to turn a shaft, creating motion.

From The Wall Street Journal • Apr. 24, 2026

The spark plug ignites a fuel-air mix, causing the rotor to turn a shaft, creating motion.

From The Wall Street Journal • Apr. 24, 2026

He also said the Flettner rotor was a "really sustainable solution" for decarbonising shipping.

From BBC • Oct. 13, 2025

A tweet about Tuesday’s announcement included a video showing a spinning wheel with a Tesla logo that could have been the rotor of a Tesla eVTOL, or quadcopter drone.

From Barron's • Oct. 7, 2025

Its rotor was broken, the grass blackened all around it.

From "Zeitoun" by Dave Eggers