tetrarchy

1. (politics) 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.Examples: "Constantius was not born to the purple and Maximianus was the only original member of the First Tetrarchy from whom Constantine could satisfactorily derive his rule."; "The abdication of Diocletian and Maximian in 305, whether long-planned or just the product of the senior emperor's recent ill health, created a second Tetrarchy, in which the dominant figure should have been Galerius."; "His imperial reorganization saw authority divided between four rulers, the Tetrarchy, to oversee the recovery."

2. (geography) The land ruled by such a government, either together or separately.Examples: "According to Josephus, Herod Agrippa, who succeeded Antipas in his Tetrarchy, died in the seventh year of his reign;[…]."; "This district was included with Galilee in the tetrarchy of Herod Antipas."; "After an adventurous career, Aristobulus' son Agrippa was appointed by Gaius, in 38 C.E., king of the former tetrarchies of Philip and Lysanias and was granted the praetorian ornamenta. Soon after, he was awarded the tetrarchy of his uncle and brother-in-law Herod Antipas[…]."