perpetual motion

noun

, Mechanics.

1. 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

noun

1. Also calledperpetual 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 calledperpetual 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

Word History and Origins

Origin of perpetual motion¹

First recorded in 1585–95

Example Sentences

“If that occurred with cloud seeding, they’d have water all the time. You can’t create rain out of thin air per se and get 6 inches of water. That’s akin to perpetual motion technology.”

From Seattle Times

And Josie might as well have been a perpetual motion machine, her head spinning around to gaze at everything in wonder, her toes tapping, her fingers fidgety.

From Literature

She’s been pop music’s premier shark, operating in near perpetual motion: Why would she pause to bask or look back, and risk losing oxygen?

From New York Times

In the spinaron effect, the cobalt atom remains in perpetual motion, maintaining its magnetic essence despite its interaction with the electrons.

From Science Daily

Her live videos record her as a perpetual motion machine, a dynamo, a volcano constantly erupting.

From BBC