Pronunciation: (ō'sāj, ō-sāj'),[key] —n., —pl.O•sag•es,(esp. collectively)O•sagefor 1. 1. a member of a North American Indian people formerly of western Missouri, now living in northern Oklahoma.
2. the Siouan language of the Osage.
3. a river flowing E from E Kansas to the Missouri River in central Missouri. 500 mi. (800 km) long.