(Jeremiah 39:3,13) a title borne by Nergal-sharezer, probably identical with the king called by the Greeks Neriglissar. [NERGAL-SHAREZER] (it probably means chief of the magi ; at all events it was "an office of great power and dignity at the Babylonian court, and probably gave its possessor special facilities for gaining the throne.")
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Smith, William, Dr. "Entry for 'Rab-mag,'". "Smith's Bible Dictionary".