/ Dictionary / Index R ribonucleoside: Meaning and Definition of Find definitions for: ri•bo•nu•cle•o•side Pronunciation: (rī"bō-n'klē-u-sīd", -ny'-), [key] — n. Biochem. a ribonucleotide precursor that contains ribose and a purine or pyrimidine base. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ribonucleoprotein ribonucleotide Related Content Daily Word Quiz: clairvoyant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language