Tetrarch

Tetrarch (Gr. tetrarchēs, Lat. tetrarcha, 'governor of the fourth part,' i.e. of a country), a title originally designating what is signified by its etymology, the governor of one of four divisions of a kingdom or country; but in the usage of the later Roman empire given undistinguishingly to all minor rulers, especially in the East, possessing sovereign rights within their territory, but dependent on the emperor, and in many cases removable at his pleasure. This was especially the case in Syria, where the princes of the family of Herod are called indiscriminately by this title (Luke, iii. 1) and by that of king (Matt. xiv. 9).