/ Dictionary / Index O Osage: Meaning and Definition of Find definitions for: O•sage Pronunciation: (ō'sāj, ō-sāj'), [key] — pl. O•sag•es, O•sage a member of a North American Indian people formerly of western Missouri, now living in northern Oklahoma. the Siouan language of the Osage. a river flowing E from E Kansas to the Missouri River in central Missouri. 500 mi. (800 km) long. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: osage (Thesaurus) O.S.A. Osage orange Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language