Noun
1. a midwestern state in central United States; a border state during the American Civil War, Missouri was admitted to the Confederacy without actually seceding from the Union
2. the longest river in the United States; arises in Montana and flows southeastward to become a tributary of the Mississippi at Saint Louis
3. a member of the Siouan people formerly inhabiting the valley of the Missouri river in Missouri
4. a dialect of the Chiwere language spoken by the Missouri people