What is the meaning of Missouri?

noun

• 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.
  • synonyms: Show Me State, MO
• The longest river in the United States; arises in Montana and flows southeastward to become a tributary of the Mississippi at Saint Louis.
  • usage: "The Missouri and Mississippi Rivers together form the third longest river in the world"
  • synonyms: Missouri River
• A member of the Siouan people formerly inhabiting the valley of the Missouri river in Missouri.
• A dialect of the Chiwere language spoken by the Missouri. .