Pronunciation: (mi-zoor'ē, -zoor'u),[key] —n., —pl.-sour•is,(esp. collectively)-sour•ifor 3. 1. a state in the central United States. 4,917,444; 69,674 sq. mi. (180,455 sq. km). Cap.: Jefferson City. Abbr.: MO (for use with zip code), Mo.
2. a river flowing from SW Montana into the Mississippi N of St. Louis, Mo. 2723 mi. (4382 km) long.
3. a member of a North American Indian tribe belonging to the Siouan linguistic stock, located on the Missouri River in early historic times and now extinct as a tribe.
4. from Missouri,Informal.unwilling to accept something without proof; skeptical: I'm from Missouri--you'll have to show me that you're right.