Literally the governor over a fourth part of a province, but also applied to the governor of any small province. It is employed in the New Testament in reference to Herod Antipas, tetrarch of Galilee and Perxa; Philip, tetrarch of Ituraea and Trachonitis; and Lysanias, tetrarch of Abilene (Matt. 14:1; Luke 3:1,19; Luke 9:7; Acts 13:1).