Definition of: Rio Negro

(rē′ō nā′grō)
1. A river in the southern Argentine Republic, flowing 400 miles east and SE to the Atlantic.
2. A river in NW Brazil, flowing SE about 1,400 miles to the Amazon.
3. A national territory of south central Argentina; 78,363 square miles; capital, Viedma.
4. A river in central Uruguay, rising in southern Brazil, and flowing 500 miles SW to the Uruguay river.