Tetracameralism

Tetracameralism (Greek: τετρα-, tetra-, "four" and Latin: camera, "chamber") is the practice of having four legislative or parliamentary chambers. It is contrasted to unicameralism, bicameralism and the rare tricameralism. No state currently has a tetracameral system. The last one ceased to exist at the beginning of the 20th century.

Medieval Scandinavian deliberative assemblies were traditionally tetracameral. The four estates were the nobility, the clergy, the burghers, and the peasants. The Swedish and Finnish Riksdag of the Estates maintained this tradition the longest, having four separate legislative bodies. Finland, as a part of Imperial Russia, used the tetracameral Diet of Finland until 1906, when it was replaced by the unicameral Parliament.