a river in Kursk Oblast, RSFSR, and in Sumy and Chernigov oblasts, Ukrainian SSR; a left tributary of the Desna (Dnieper River basin). The Seim is 748 km long and drains an area of 27,500 sq km. Originating on the Central Russian Upland, the Seim flows in a wide valley; the floodplain contains many oxbow lakes. The river is fed primarily by snow. The mean flow rate 105 km from the mouth is 99.6 cu m per sec. The Seim freezes between late November and early January, and the ice breaks up in late March or early April. There is local navigation in the lower course. The cities of Kursk, L’gov, Ryl’sk, and Putivl’ are on the Seim.

(Russian transliteration; Polish sejm, Lithuanian seimas, Czech snĕ m). (1) A representative institution of the estates in Bohemia, in the feudal monarchies of Poland and Lithuania, and in the united Polish-Lithuanian state, the Rzeczpospolita; seimy arose in the 13th and 14th centuries and endured until the early 20th century.

(2) The Russian name of the Diet in the Grand Duchy of Finland (1809–1917), an autonomous part of the Russian empire.

(3) The parliament in bourgeois Lithuania from 1922 to 1940 (1922 constitution), the parliament in bourgeois Latvia from 1922 to 1934 (1922 constitution), and the lower house of parliament in bourgeois Poland (1921 constitution).

(4) In the Polish People’s Republic (1952 constitution), the supreme organ of state power and the only legislative body. The Sejm is elected every four years (seePOLAND: Constitution and government).