| OSA | the Dhegiha dialect spoken by the Osage people |
|---|---|
| OSA | a river in Missouri that is a tributary of the Missouri River |
| OSA | a member of the Siouan people formerly living in Missouri in the valleys of the Missouri and Osage rivers |
| OSA | small shrubby deciduous yellowwood tree of south central United States having spines, glossy dark green leaves and an inedible fruit that resembles an orange |
| OSA | a river in Missouri that is a tributary of the Missouri River |
| OSA | port city on southern Honshu on Osaka Bay |
| OSA | a bay of the western Pacific in southern Honshu Island in Japan |
| OSA | a city in southeastern Brazil |