From en.wiktionary.org:
** English
*** Noun
[-]
1. [en] The motion of some hypothetical device that continue s forever with no external input of energy , in violation of the law s of thermodynamics .
**** Usage notes
- In the literal sense, perpetual motion can exist in an ideal isolated system , such as a single photon moving through empty space. However, a perpetual motion machine which produces work while retaining its kinetic energy is impossible under the known laws of physics.
**** Derived terms
- [en]
**** Translations
[trans-top]
- Finnish: [fi]
- French: [fr]
- Latin: [la]
- Polish: [pl] , [pl]
- Russian: [ru]
[trans-bottom]
*** Further reading
- [pedia]
- [Laws of thermodynamics]