/ Dictionary / Index N nuclear reaction: Meaning and Definition of Find definitions for: nu'clear reac'tion Pronunciation: [key] reaction (def. 8). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. nuclear radiation nuclear reactor Related Content Daily Word Quiz: mamba Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language