/ Dictionary / Index P polyribosome: Meaning and Definition of Find definitions for: pol•y•ri•bo•some Pronunciation: (pol"ē-rī'bu-sōm"), [key] — n. Biol. polysome. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. polyrhythm polysaccharide Related Content Daily Word Quiz: knead Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language