/ Dictionary / Index N nebulium: Meaning and Definition of Find definitions for: ne•bu•li•um Pronunciation: (nu-by'lē-um), [key] — n. Astron. a hypothetical element once thought to be present in emission nebulae because of certain unidentified spectral lines, now known to be forbidden transitions of oxygen and nitrogen ions. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. nebulated nebulize Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language