Dictionary.com

perpetual-motion machine

Save This Word!

A machine that could run forever. A perpetual-motion machine would have to produce at least as much energy as was needed for its operation. According to the second law of thermodynamics, such a machine is impossible, and to date none has ever been successfully demonstrated.

QUIZ
GOOSES. GEESES. I WANT THIS QUIZ ON PLURAL NOUNS!
Test how much you really know about regular and irregular plural nouns with this quiz.
Question 1 of 9
Which of the following nouns has an irregular plural form?
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

How to use perpetual-motion machine in a sentence

FEEDBACK