HyperDic: perpetual_motion_machine

English > 1 sense of the expression *perpetual motion machine*:
NOUN	artifact	perpetual motion machine	a machine that can continue to do work indefinitely without drawing energy from some external source

English > *perpetual motion machine*: 1 sense > noun 1, artifact
Meaning	A machine that can continue to do work indefinitely without drawing energy from some external source; impossible under the law of conservation of energy.
Broader	machine	Any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of human tasks