Boyd’s Bible Dictionary:
(king). Hardly a proper name (Jer. 36:26; 38:6).
Concise Bible Dictionary:
Father of Jerahmeel and Malchiah, as in the AV. The word is considered by some not to be a proper name, but to signify “the king,” reading “Jerahmeel, the king’s son,” and “Malchiah, the king’s son” (Jer. 36:26; Jer. 38:6); as in the margin and the RV.
Jackson’s Dictionary of Scripture Proper Names:
the king