/ Dictionary / Index D diffuse nebula: Meaning and Definition of Find definitions for: diffuse' neb'ula Pronunciation: [key] — Astron. Astron. nebula (def. 1a). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. diffuse diffuse-porous Related Content Daily Word Quiz: diaphanous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language