# rotor

/ˈɹoʊtɝ/ (US) · /ɹˈəʊtɐ/ (UK)

Source: https://englishreference.com/word/rotor
Updated: 2026-08-08

## Senses

### 1. mechanical part

noun · CEFR C1 · Technical

the part of a machine that spins around to make it work.

For teachers: the rotating part of a mechanical device, such as an electric motor, generator, or pump.

- The mechanic had to replace the rotor inside the car's alternator.
- The engineer identified a hairline fracture in the main rotor, which explained the excessive vibration during high-speed operation.

Usage: In electrical engineering, it is often contrasted with the 'stator', which is the stationary part of the machine.

### 2. aviation

noun · CEFR C1 · Technical

the large spinning blades on top of a helicopter that help it fly.

For teachers: a system of rotating aerofoils, such as those on a helicopter, used to provide lift and control.

- The helicopter's rotor started spinning faster as it prepared for takeoff.
- The pilot adjusted the pitch of the tail rotor to counteract the torque produced by the main blades.

Teaching tip: While 'propeller' is used for planes, 'rotor' is the standard term for the lifting blades of a helicopter.

### 3. mathematics

noun · CEFR C2 · Technical · Academic

a mathematical value that has a size, a direction, and a specific location.

For teachers: a quantity possessing magnitude, direction, and a specific line of action or position.

- The professor explained how to calculate the rotor in the physics problem.
- The student struggled to differentiate between a simple vector and a rotor when mapping the forces across the rigid body.

### 4. weather

noun · CEFR C2 · Technical

a strong, spinning wind that forms near mountains.

For teachers: a powerful horizontal-axis atmospheric vortex created when strong winds interact with mountainous terrain.

- Pilots are warned to avoid the dangerous rotors that form behind the mountain peaks.
- The glider was caught in a violent mountain rotor, forcing the pilot to perform an emergency maneuver to regain stability.

## Examples

- The helicopter's rotor started to spin faster.
- Engineers inspected the tail rotor for cracks after the pilot reported unusual vibrations during the landing.
- The efficiency of a wind turbine depends largely on the aerodynamic design of its rotor, which must capture maximum kinetic energy from varying wind speeds.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.