from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A heavy-rimmed rotating wheel used to minimize variations in angular velocity and revolutions per minute, as in a machine subject to fluctuation in drive and load.
  • noun An analogous device, especially one used to regulate the speed of clockwork.

from The Century Dictionary.

  • noun In machinery, a wheel with a heavy rim placed on the revolving shaft of any machinery put in motion by an irregular or intermitting force or meeting with an irregular or intermittent resistance, for the purpose of rendering the motion equable and regular by means of its momentum.

from the GNU version of the Collaborative International Dictionary of English.

  • noun A heavy wheel or disk which stores kinetic energy by rotating on a shaft, and by its momentum smoothes the operation of a reciprocating engine by reducing fluctuations of speed. It is used in certain types of machinery, such as automobiles.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun a rotating mass used to maintain the speed of a machine within certain limits while the machine receives or releases energy at a varying rate

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun regulator consisting of a heavy wheel that stores kinetic energy and smooths the operation of a reciprocating engine


from Wiktionary, Creative Commons Attribution/Share-Alike License

fly + wheel



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  • Used by Roger Ebert in his 2011 memoir, Life Itself, in a way I can't find a good definition for: "…Aleister Crowley…was a flywheel but surely wrote one of the best Edwardian autobiographies…" (204).

    December 10, 2011

  • Perhaps Ebert was suggesting that Crowley moved under his own inertia, by his own (some would think) strange lights, throwing off energy as he spun through life.

    December 10, 2011