/ Dictionary / Index C conservation of energy: Meaning and Definition of Find definitions for: conserva'tion of en'ergy Pronunciation: [key] — Physics. Physics. the principle that in a system that does not undergo any force from outside the system, the amount of energy is constant, irrespective of its changes in form. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. conservation of charge conservation of lepton number Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language