a former empire in eastern Europe and northern Asia created in the 14th century with Moscow as the capital; powerful in the 17th and 18th centuries under Peter the Great and Catherine the Great when Saint Petersburg was the capital; overthrown by revolution in 1917 a former communist country in eastern Europe and northern Asia; established in 1922; included Russia and 14 other soviet socialist republics (Ukraine and Byelorussia and others); officially dissolved 31 December 1991 a federation in northeastern Europe and northern Asia; formerly Soviet Russia; since 1991 an independent state formerly the largest Soviet Socialist Republic in the USSR occupying eastern Europe and northern Asia