(n´str) (KEY) , Rus. Dnestr, Ukr. Dnister, river, c.850 mi (1,370 km) long, forming part of the border between Ukraine and Moldova. It rises in the Carpathian Mts., flows generally SE through SW Ukraine past Halych, Khotin, and Mohyliv-Podilskyy, through Moldova past Tighina and Tiraspol, and empties through an estuary into the Black Sea SW of Odessa. It is navigable below Halych; its tributaries include the Sereth and the Stryy. The Dniester formed the Romanian-Soviet border from 1918 to 1940, when the USSR regained Bessarabia.