From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

("king's stare".) (An oriental phrase), an Ethiopian eunuch of king Zedekiah, instrumental in Jeremiah's deliverance out of Malchiah's dungeon pit. Ebed-melech, an Ethiopian Gentile slave, did that which none of Jeremiah's own countrymen attempted in his behalf. Often God raises friends to His people from quarters from whence least they could expect it. Ebedmelech's courageous interference in Jeremiah's behalf, at a time when he might naturally fear the wrath of the princes to which even the king had to yield ( Jeremiah 38:4-13;  Jeremiah 39:16-18), brought deliverance not only to the prophet, but ultimately to himself as his reward from God.

None ever loses by being bold for God ( Matthew 10:42). He might have spoken privately to the king, as being over the king's harem (Nubians being chosen for that office to the present day), but Ebed-melech "went forth out of the king's house to the gate of Benjamin," and there spoke publicly to the king, "these men have done evil in all that they have done to Jeremiah whom they have cast into the dungeon, and he is like to die for hunger in the place where he is, for there is no more bread in the city."

With 30 men to guard against the princes' opposition, and by means of torn clothes and worn garments ("cast clouts and rotten rags," for God chooses weak things to confound the mighty,  1 Corinthians 1:27-29), he raised Jeremiah up from the pit. So when his enemies should perish God promised Ebedmelech should be saved, "because thou hast put thy trust in Me" (compare  1 Chronicles 5:20;  Psalms 37:40). Trust in God generates fearlessness of man and brings true safety for eternity, and often even here (Jeremiah 39). So shall they be rewarded who have visited Christ, in the person of His servants, in prison ( Matthew 25:34 ff).

People's Dictionary of the Bible [2]

Ebed-melech. ( Ç'Bed-Mç'Lek ), ( Thing'S Servant, an Ethiopian eunuch in the service of King Zedekiah, through whose interference Jeremiah was released from prison.  Jeremiah 38:7 ff;  Jeremiah 39:15-16.

Hastings' Dictionary of the Bible [3]

Ebed-Melech . An Ethiop. ennuch, by whom Jeremiah was released from the pit-prison (  Jeremiah 38:7 ff;   Jeremiah 39:15 ff.). It is possible that the name Ebed-melech , which means ‘servant of [the] king.’ may have been an official title.

American Tract Society Bible Dictionary [4]

An Ethiopian servant of king Zedekiah, who was instrumental in saving the prophet Jeremiah from famishing in a filthy dungeon, and was therefore preserved when Jerusalem was taken by Nebuzaradan,  Jeremiah 38:7-13;  39:15-18 . The Lord knoweth them that are his.

Smith's Bible Dictionary [5]

E'bed-me'lech. (A King'S Servant). An Ethiopian eunuch, in the service of King Zedekiah, through whose interference Jeremiah was released from prison.  Jeremiah 38:7. ff.;  Jeremiah 39:15. ff. (B.C. 1589).

Hawker's Poor Man's Concordance And Dictionary [6]

This man is spoken of with honourable testimony in Scripture, for his service to the prophet Jeremiah. His name shews who he was, Ebed, a servant, Melech, to the king. (See  Jeremiah 38:7-13)

Holman Bible Dictionary [7]

 Jeremiah 38:7 Jeremiah 39:15-18

Easton's Bible Dictionary [8]

 Jeremiah 38:7-13

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [9]

(Hebrews E'bed-Me'lek, עֶבֶדמֶלֶךְ , Servant Of the King, i.e., Arabic Abd El-Malek, Sept. Ἀβδεμέλεχ ,Vulgate Abdemelech ), an Ethiopian at the court of Zedekiah, king of Judah, who was instrumental in saving the prophet Jeremiah from death by famine ( Jeremiah 38:7-13), and who, for his humanity in this circumstance, was promised deliverance when the city should fall into the enemy's hands ( Jeremiah 39:15-18). B.C. 589. (See Jeremiah). He is there styled a eunuch ( אַישׁ סָרַיס and he probably had charge of the king's harem (compare  Jeremiah 38:22-23), an office which would give him the privilege of free private access to the king; but his name seems to be an official title = King'S Slave, i.e., Minister . (See Eunuch).

International Standard Bible Encyclopedia [10]

ē - bed - mē´lek , eb - ed - mē´lek ( עבד־מלך , ‛ebhedh - mekekh , "servant of the king" or "of (god) Melek"): An Ethiopian eunuch in the service of King Zedekiah, who interceded with the king for the prophet Jeremiah and rescued him from the dungeon into which he had been cast to die ( Jeremiah 38:7-13 ). For this, the word of Yahweh through Jeremiah promised Ebed-meleeh that his life should be spared in the fall of Jerusalem ( Jeremiah 39:15-18 ).