A river of South America, which rises as the River Guainia in eastern Colombia and flows for about 2,255 km (1,400 miles) through north-western Brazil before joining the River Amazon near Manaus.
Definition of Rio Negro in US English:
Rio Negro
proper nounˌrēō ˈnāɡrō
A river in South America that rises as the Guainia River in eastern Colombia and flows for about 1,400 miles (2,255 km) through northwestern Brazil before joining the Amazon River near Manaus.