Joab means in the bible: 1 Eldest child of Zeruiah (Zeruiah’s sister) and Captain of David’s Army. He was close to all of the major events during David’s reign, and was faithful to his master. He was for Adonijah’s succession after David died 1 Kgs. Solomon was able to execute David at 2:28, and he did so for the following reasons: 2:29-34.
(in Bible Dictionary)