big sioux river is a noun meaning "a river that rises in northeastern South Dakota and flows southward to join the Missouri River at Sioux City, Iowa". It carries one recorded sense.
a river that rises in northeastern South Dakota and flows southward to join the Missouri River at Sioux City, Iowa
Definitions, synonyms and semantic relations for big sioux river come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.