/ Dictionary / Index N nuclear emulsion: Meaning and Definition of Find definitions for: nu'clear emul'sion Pronunciation: [key] — Physics. Physics. a photographic emulsion in the form of a thick block, used to record the tracks of elementary particles. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. nuclear cross section nuclear energy Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language