Longman Dictionary of Contemporary English homepage

perpetual motion

 noun
     
perpetual motion [uncountable]
the ability of a machine to always continue moving without getting energy from anywhere else, which is not considered possible
Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.

Dictionary pictures of the day
Do you know what each of these is called?
What is the word for picture 1? What is the word for picture 2? What is the word for picture 3? What is the word for picture 4?
Click on any of the pictures above to find out what it is called.

Explore our topic dictionary

Browse the dictionary