In 16th and 17th century Russia: a national assembly, convened (usually by the tsar) for particular purposes, and consisting of representatives of the aristocracy and landowners, the ecclesiastical authorities, and the merchants and free citizens of the towns.
The Zemsky Sobor was established under Ivan the Terrible in the mid 16th century, but its importance declined after the 1620s. By the end of the century it had ceased to operate as a national body, although its revival has been proposed on several occasions.
Late 19th century; earliest use found in The Times. From Russian zemskij sobor ecclesiastical council, national assembly from zemskij (adjective) of land (from zemlja land, earth) + sobor assembly.