Since the Second Polish Republic (1918–1939), "Sejm" has referred only to the lower house of the parliament; the upper house is called the Senat Rzeczypospolitej Polskiej ("Senate of the Republic of Poland").
İkinci Polonya Cumhuriyeti'nden (1918–1939) beri, "Sejm" yalnızca parlamentonun alt meclisi oldu; üst meclise Senat Rzeczypospolitej Polskiej ("Polonya Cumhuriyeti'nin Senatosu") denir.