DUKE (Heb. ’allûph and nāsîkh). These Hebrew words are sometimes rendered “duke” (especially when used of the leaders of the Edomites), “princes,” “principal men,” and “governor” in the KJV. In general, they mean a leader of a clan or a tribal chief. NIV usually translates “chief.” See Gen.36.15-Gen.36.16; Exod.15.15; Josh.13.21; 1Chr.1.51-1Chr.1.52.
International Standard Bible Encyclopedia (1915)
Moreover, at the time the King James Version was made the word "duke" was not used as a title in England: the term had the same general force as dux, the word employed in the Vulgate (Jerome’s Latin Bible, 390-405 A. D.) So Sir T. Elyot (died 1546) speaks of "Hannibal, duke of Carthage" ( The Governor, II, 233); Shakespeare, Henry V, III, 2, 20, "Be merciful, great duke, to men of mould" (compare Midsummer Night’s Dream, I, 1, 21); Sylvester (1591) Du Bartas, "The great Duke, that in dreadful aw upon Mt. Horeb learned the eternal law." In a still earlier age Wycliff uses the word of the Messiah (Mt 2:6); and in Select Works, III, 137, "[[Jesus Christ]], duke of oure batel."
Yet in all probability the Hebrew word was more specific than "chief" or "duke" in the broad sense. For if ’alluph is derived from ’eleph, "thousand," "tribe," the term would mean the leader of a clan, a "chiliarch" (compare Septuagint, Zec 9:7; 12:5,6). the American Standard Revised Version has eliminated the word "duke." See [[Chief]].
J. R. Van Pelt