/ Thesaurus / O Synonyms of o'casey Find synonyms for: Noun1. O'Casey, Sean O'Caseyusage: Irish playwright (1880-1964)WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language