​ISHIM, a town of West Siberia, in the government of Tobolsk, 180 m. N.W. of Omsk, on a river of the same name, tributary, on the left, of the Irtysh. Pop. (1897) 7161. The town, which was founded in 1630, has tallow-melting and carries on a large trade in rye and rye flour. The fair is one of the most important in Siberia, its returns being estimated at £500,000 annually.