Raddai is the fifth son of Jesse, and older brother of David (1 Chronicles 2:14). He's mentioned but plays no further role in the Bible.
The name Raddai looks like an imperative of the verb (yarad), go down. It's used as such in Isaiah 47:1 and Jeremiah 48:18: Come down...!
BDB Theological Dictionary and others however suggest that the name Raddai comes from the verb (radad), beat down, subdue (Isaiah 45:1, Psalm 144:2). The added yod, some suggest, is a remnant of the name of the Lord YHWH.
For a meaning of the name Raddai, NOBS Study Bible Name List reads Yahweh Has Subdued. Jones' Dictionary of Old Testament Proper Names reads simply Subduing.
(yarad), go down. It's used as such in Isaiah 47:1 and Jeremiah 48:18: Come down...!
(radad), beat down, subdue (Isaiah 45:1, Psalm 144:2). The added yod, some suggest, is a remnant of the name of the Lord 
