/ Dictionary / Index R radiant energy: Meaning and Definition of Find definitions for: ra'diant en'ergy Pronunciation: [key] — Physics. Physics. energy transmitted in wave motion, esp. electromagnetic wave motion. light (def. 2a). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radiant emittance radiant flux Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language