perpetual motion

American

noun

Mechanics.

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.

perpetual motion British

noun

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
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 & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of perpetual motion

First recorded in 1585–95

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Mario is thus an ideal avatar: Cheerful, active, in perpetual motion and vague enough to represent whatever a gamer wants him to be.

From The Wall Street Journal

Even so, it feels criminal to compare it with the band’s earlier catalog, given that Hewlett and Albarn are artists in “perpetual motion.”

From Los Angeles Times

While taking no action is always an option for true long-term investors, many others feel they must be in perpetual motion.

From Barron's

The objective of the value investor like Buffett is to make money over the long term, but the manner in which this is accomplished is also in perpetual motion.

From Barron's

Just like the North Star and all its whirling, starry brethren, a person’s idea of where “home” is remains in perpetual motion, one’s whole life long.

From Literature

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023