/ Dictionary / Index N nuclear energy: Meaning and Definition of Find definitions for: nu'clear en'ergy Pronunciation: [key] energy released by reactions within atomic nuclei, as in nuclear fission or fusion. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. nuclear emulsion nuclear family Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language