a fortified town of Russian Poland, in the government of Lublin, 64 m. by rail S.E. from Warsaw, at the confluence of the Wieprz with the Vistula. It is defended by nine forts on the right bank of the Vistula and by three on the left bank, and, with Warsaw, Novo-Georgievsk and BrestLitovsk, forms the Polish "quadrilateral."