Lexicon :: Strong's G5076 - tetraarchēs

τετράρχης (T WH τετραάρχης; see the preceding word, and cf. Tdf. Proleg., p. 117), τετράρχου, ὁ (from τέτρα, which see, and ἄρχω), a tetrarch; i. e.
1. a governor of the fourth part of any region. Thus Strabo, 12, p. 567, states that Galatia was formerly divided into three parts, each one of which was distributed into four smaller subdivisions each of which was governed by 'a tetrarch'; again, in book 9, p. 430, he relates that Thessaly, before the time of Philip of Macedon, had been divided into four 'tetrarchies' each of which had its own 'tetrarch'.
2. the word lost its strict etymological force, and came to denote "the governor of a third part or half of a country, or even the ruler of an entire country or district provided it were of comparatively narrow limits; a petty prince" (cf. e. g. Plutarch, Anton. 56, 3, i., p. 942 a.). Thus Antony made Herod (afterward king) and Phasael, sons of Antipater, tetrarchs of Palestine, Josephus, Antiquities 14, 13, 1. After the death of Herod the Great, his sons, Archelaus styled an ethnarch but Antipas and Philip with the title of 'tetrarchs', divided and governed the kingdom left by their father; Josephus, Antiquities 17, 11, 4. Cf. Fischer, De vitiis etc., p. 428; Winers RWB, under the word Tetrarch, and especially Keim in Schenkel v., p. 487ff The tetrarch Herod Antipas is mentioned in Matthew 14:1; Luke 3:19; Luke 9:7; Acts 13:1.

BLB Scripture Index of Thayer's