/ Dictionary / Index O Onassis: Meaning and Definition of Find definitions for: O•nas•sis Pronunciation: (ō-nas'is, ō-nä'sis), [key] — n. 1906–75, Greek businessman, born in Turkey. (“Jackie”), 1929–94, wife of John F. Kennedy (1953–63) and Aristotle Onassis (1968–75). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. onanism Oñate Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language