/ Dictionary / Index P platiniridium: Meaning and Definition of Find definitions for: plat•in•i•rid•i•um Pronunciation: (plat"n-i-rid'ē-um, -ī-rid'-), [key] — n. a natural alloy composed chiefly of platinum and iridium. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. platinic chloride Platinite Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language