Webster's Dictionary 
(1): ( n.) A commissioned officer in the army, next below a captain.
(2): ( n.) A commissioned officer in the British navy, in rank next below a commander.
(3): ( n.) A commissioned officer in the United States navy, in rank next below a lieutenant commander.
(4): ( n.) An officer who supplies the place of a superior in his absence; a representative of, or substitute for, another in the performance of any duty.
Holman Bible Dictionary 
Easton's Bible Dictionary 
Esther 3:12 8:9 9:3 Ezra 8:36
Hastings' Dictionary of the Bible 
Lieutenant See Satrap.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
(only in the plur. אֲחִשְׁדִּרְפְּנַים , Achashdaspenin', from the Sanscrit Ksatrapa,Whence the Greek Ἐξατράπης , and finally Σατράπης , a Satrap, see Gotting. Gel. Anz. 1839, page 805; Lassen, Zeitschr. F '''''Ü''''' R D Morgenl. 3:161; Bockh, Corpus Inscr. No. 2691, c) occurs in Esther 3:12; Esther 8:9; Esther 9:3; Ezra 8:38; so in the Chald. form (rendered "princes," Daniel 3:2-3; Daniel 3:27; Daniel 6:1-7) a satrap, i.e. governor or viceroy of the large provinces among the ancient Persians, possessing both civil and military power, and being in the provinces the representatives of the sovereign, whose state and splendor they also rivalled (see Brisson, De regio Pers. principatu, 1, § 168; Heeren, Ideen, 1:489 sq.). (See Satrap).