perpetual motion

Also found in: Thesaurus, Acronyms, Encyclopedia, Wikipedia.

perpetual motion

The hypothetical continuous operation of an isolated mechanical device or other closed system without a sustaining energy source.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

perpetual motion

1. Also called: perpetual motion of the first kind motion of a hypothetical mechanism that continues indefinitely without any external source of energy. It is impossible in practice because of friction

2. Also called: perpetual motion of the second kind motion of a hypothetical mechanism that derives its energy from a source at a lower temperature. It is impossible in practice because of the second law of thermodynamics

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

perpet′ual mo′tion

the motion of a theoretical mechanism that, without any losses due to friction or other forms of dissipation of energy, would continue to operate indefinitely at the same rate without any external energy being applied to it.

[1585–95]

ThesaurusAntonymsRelated WordsSynonymsLegend:

Switch to new thesaurus

Noun

perpetual motion - motion that continues indefinitely without any external source of energy; impossible in practice because of friction

motion - a state of change; "they were in a state of steady motion"

Mentioned in ?

References in classic literature ?

I can no more tell you the whys and wherefores of myself than I can lift myself up by the waistband and carry myself into the next county, as some one challenged a speculator in perpetual motion to do.

View in context

"There have been eccentric inventors, starving their families while they sought such chimeras as perpetual motion. Doubtless their wives loved them, and suffered with them and for them, not because of but in spite of their infatuation for perpetual motion."

"To you, then, my goal is as much a chimera as perpetual motion?" he demanded.

View in context

It would be a flight beyond his usual foolery to seek for the perpetual motion; and yet I know enough of my old business to be certain that what he is now so busy with is no part of the machinery of a watch."

"Folks do say that you are trying to discover the perpetual motion."

"The perpetual motion? Nonsense!" replied Owen Warland, with a movement of disgust; for he was full of little petulances.

I was afraid your perpetual motion had bewitched you out of the remembrance of old times."

View in context

The discovery of this Behoving Machine was the discovery of the political perpetual motion. It never wore out, though it was always going round and round in all the State Departments.

View in context

There was not the slightest necessity for the greater portion of the labour performed by the old lady: but she seemed to work from some irresistible impulse; her limbs continually swaying to and fro, as if there were some indefatigable engine concealed within her body which kept her in perpetual motion.

View in context

'The have-his-carcass, next to the perpetual motion, is vun of the blessedest things as wos ever made.

View in context

Careful adjustment of the timing of exposure may reduce early-phase movement and perpetual motion of the diaphragm, while hyperventilation or physical aids such as oxygen inspiration may reduce late-phase movement.

Types of diaphragmatic motion during hepatic angiography

Perpetual Motion People is full of life and shot through with joy from beginning to end.