A government where power is shared by four people, especially (historical) the Herodian tetrarchy established in Judea after the death of Herod and the Tetrarchy of Diocletian which ruled the Roman Empire in the years 293-313.
The land ruled by such a government, either together or separately.
A group of eleven people, especially (politics) a council of eleven men sharing office or power and particularly (historical) the groups of eleven magistrates in ancient Athens.