Smith's Bible Dictionary (1863)
(excellence), an Israelite, (2 Samuel 17:25) or Ishmaelite, (1 Chronicles 2:17) the father of Amasa by Abigail, David’s sister.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
ITH'RA (abundance), David's brother-in-law. 2 Sam 17:25. See Jether.