/ Thesaurus / P Synonyms of pius xi Find synonyms for: Noun1. Pius XI, Achille Ratti, Ambrogio Damiano Achille Rattiusage: pope who signed a treaty with Mussolini recognizing the Vatican City as an independent state (1857-1939)WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: feline Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language