flywheel

noun

fly·​wheel ˈflī-ˌ(h)wēl 

: a heavy wheel for opposing and moderating by its inertia any fluctuation of speed in the machinery with which it revolves

also : a similar wheel used for storing kinetic energy (as for motive power)

Did you know?

A heavy wheel attached to a rotating shaft, a flywheel smooths out delivery of power from a motor to a machine. The inertia of the flywheel moderates fluctuations in the speed of the engine and stores the excess energy for intermittent use. In automobile engines, the flywheel smooths out the pulses of energy provided by combustion in the cylinders, and provides energy for the compression stroke of the pistons. In power presses, the punching, shearing, and forming are done in a fraction of the operating cycle. During the rest of the cycle, the speed of the flywheel is built up by a comparatively low-powered motor, and most of the required energy for the cycle is provided by the flywheel.

Examples of flywheel in a Sentence

Recent Examples on the Web

That’s what makes this flywheel go around. —James Manso, Footwear News, 18 Nov. 2025

Regardless, the headlines around its chart-topping have created a flywheel effect, creating more interest and outrage around the song. —Andrew R. Chow, Time, 14 Nov. 2025

This created enough of a temperature gap to activate the piston and spin the flywheel. —Aamir Khollam, Interesting Engineering, 13 Nov. 2025

Each corporate client adds new evaluators, and each evaluator helps refine more models, creating a flywheel of both data and demand. —Eva Roytburg, Fortune, 12 Nov. 2025

Word History

First Known Use

1784, in the meaning defined above

Rhymes for flywheel

• abele
• alkyl
• anneal
• appeal
• cartwheel
• conceal
• congeal
• coquille
• corneal
• cornmeal
• foveal
• genteel

Kids Definition

flywheel

noun

fly·​wheel -ˌhwēl  -ˌwēl 

: a heavy wheel for regulating the speed of machinery