/ Dictionary / Index P piro: Meaning and Definition of Find definitions for: pir•o Pronunciation: (pir'ō), [key] — n. Informal. piroplasmosis. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pirn pirogen Related Content Daily Word Quiz: pugilist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language