- a river in NW South America, flowing SE from S Colombia into the Amazon in NW Brazil. 900 miles (1,450 km) long.
- a river in NW South America, rising in S Colombia and flowing southeast as most of the border between Colombia and Peru, entering the Amazon in Brazil: scene of the Putumayo rubber scandal (1910–11) during the rubber boom, in which many Indians were enslaved and killed by rubber exploiters. Length: 1578 km (980 miles)
