either of two rivers now in southwestern Poland (until 1945, in Germany). The better-known Nysa Łużycka, or Lusatian Neisse, is the longer (157 miles 【252 km】) and more westerly; it forms part of the German-Polish frontier (see Oder–Neisse Line). The Nysa Kłodzka (Glatzer Neisse), or Neisse of the city of Kłodzko (Glatz), is the shorter (113 miles 【182 km】) and lies entirely within Poland. Both rise in the Sudeten mountains, flow northward, and empty into the Oder River.