O’Neill (?-n?l?), Eugene Gladstone 1888-1953. American playwright. Among his works are Mourning Becomes Electra (1931) and Long Day’s Journey into Night (produced 1956), for which he was awarded his fourth Pulitzer Prize. He won the 1936 Nobel Prize for literature.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.