Omsk (ômsk), city (1989 pop. 1,148,000), capital of Omsk region, W Siberian Russia, at the confluence of the Irtysh and Om rivers and on the Trans-Siberian RR. It is a major river port and produces agricultural machinery and railway equipment. There are also oil refineries supplied by pipelines from the West Siberian basin. Factories in Omsk also produce footwear, clothing, tires, and consumer goods. Founded as a fortress in 1716, Omsk became a major transportation and administrative center in the 19th cent. and a place of detention for political exiles. Feodor Dostoyevsky was imprisoned there from 1849 to 1853. During the civil war that followed the Revolution of 1917, Omsk served as headquarters of the anti-Bolshevik armed forces of Admiral A. V. Kolchak.