river basin is a noun meaning "the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet". It carries one recorded sense.
the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet
“flood control in the Missouri basin”
Definitions, synonyms and semantic relations for river basin come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.