(Polish Orsza), a town of Russia, in the government of Mogilev, 74 m. by rail W.S.W. of Smolensk on the MoscowWarsaw railway, and on the Dnieper. Pop. (1897), 13,161. It is an important entrepot for grain, seeds and timber. It is a very old town, mentioned in the annals under the name of Rsha in 1067. In the 13th century it was taken by the Lithuanians, who fortified it. In 1604 the Poles founded there a Jesuit college. The Russians besieged Orsha more than once in the 16th and 17th centuries, and finally annexed it in 1772.