/ Thesaurus / O Synonyms of o'neill Find synonyms for: Noun1. O'Neill, Eugene O'Neill, Eugene Gladstone O'Neillusage: United States playwright (1888-1953)WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: tenacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language