Also found in: Wikipedia.
a river in Central Africa, in Zaire, a left tributary of the Congo River (locally Zaire). Formed by the confluence of the Busira (whose sources are the Tshuapa, Lomela, and Solonga rivers) and Momboyo (Luilaka in its upper reaches) rivers. Its length is 105 km if measured from the site of the confluence and approximately 1,300 km if measured from the Tshuapa’s source. The river drains an area of 173,800 sq km. The Ruki and the rivers that form it flow through dense equatorial forests and broad, mostly swampy valleys. The slope of the river’s channels is not pronounced. The Ruki is fed by rain and is full year round; its maximum flow rates occur from October through December and from April through June. The Ruki-Busira-Tshuapa system is navigable for 1,108 km; the Ruki’s principal tributaries are also navigable.