| perpetual motion n. The hypothetical continuous operation of an isolated mechanical device or other closed system without a sustaining energy source. |
perpetual motion
n
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
ThesaurusLegend: Synonyms Related Words Antonyms
| Noun | 1. |  perpetual motion - motion that continues indefinitely without any external source of energy; impossible in practice because of frictionmotion - a state of change; "they were in a state of steady motion" |
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