| perpetual motion | (n) motion that continues indefinitely without any external source of energy; impossible in practice because of friction |
| perpetual motion machine | (n) a machine that can continue to do work indefinitely without drawing energy from some external source; impossible under the law of conservation of energy |
| 永久機関 | [えいきゅうきかん, eikyuukikan] (n) perpetual motion [Add to Longdo] |