The king’s, the father of Jerahmeel, mentioned in Jer. 36:26.
Some take this word as a common noun, “the king”, and understand
that Jerahmeel was Jehoiakim’s son. Probably, however, it is to
be taken as a proper name.
Smith's Dictionary
lit. “the king, ” unnecessarily rendered in the Authorized Version as a proper name. (Jeremiah 36:26; 38:6)