/ Dictionary / Index R rough endoplasmic reticulum: Meaning and Definition of Find definitions for: rough' endoplas'mic retic'ulum. Pronunciation: [key] See under Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. roughen rougher Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language