/ Dictionary / Index P Pius XI: Meaning and Definition of Find definitions for: Pius XI Pronunciation: [key] (Achille Ratti) 1857–1939, Italian ecclesiastic: pope 1922–39. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Pius X Pius XII 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