/ Dictionary / Index P polychasium: Meaning and Definition of Find definitions for: pol•y•cha•si•um Pronunciation: (pol"ē-kā'zhē-um, -zhum, -zē-um), [key] — pl. -si•a a form of cymose inflorescence in which each axis produces more than two lateral axes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. polychaete polychlorinated biphenyl Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language