TETRARCH. - Originally, and according to the etymology, the head of one of the four regions of a province, or also one who shared command with three others; tetrarchy was the authority, office, or territory of the t.
Euripides (d. 406 B.C.) was the first to speak of tetrarchy in relation to Thessaly. Strabo (d. A.D. 20) attests that each of the tribes of Galatia was governed by 4 t. But around 85 B.C. a single chief commanded an entire tribe, while retaining the title of t.; thereafter its original meaning was lost, until it indicated only the ruler of a region not very extensive, of rank inferior to the king and the ethnarch (v.), though some enjoyed certain of their privileges. In this sense it was frequently employed by the Romans, especially for the small states of Syria.
Herod (v.) the Great and his brother Phasael received from Antony the title of t. (respectively of Galilee and Judaea) as early as 41 B.C. T. is in the New Testament the ordinary title of Herod Antipas (Mt. 14, 1; Lc. 3, 1. 19; 9, 7; Act. 13, 1), though he is sometimes also called king (Mt. 14, 9; Mc. 6, 14. 22. 25 sgg.), certainly according to popular usage; Lc. 3, 1 gives the same title of t. to Herod Philip, son of Herod the Great: indeed, both Antipas and Herod Philip had each inherited one of the four parts of the Kingdom of Herod the Great, while Archelaus had received the other two parts with the title of ethnarch. Lc. 3, 4 Lysanias (v.), t. Abilene (v.).