Rephaim ref'-a-im, re-fa'-im (repha'-im, from rapha', "a terrible one "hence "giant," in 1 Chronicles 20:4, yelidhe ha-rapha', "sons of the giant"; the King James Version, Rephaims): A race of aboriginal or early inhabitants East of the Jordan in Ashterothkarnaim (Genesis 14:5) and in the valley of Rephaim Southwest of Jerusalem (Joshua 15:8). They associated with other giant races, as the Emim and Anakim (Deuteronomy 2:10, Deuteronomy 2:11) and the Zamzummim (Deuteronomy 2:20). It is probable that they were all of the same stock, being given different names by the different tribes who came in contact with them. The same Hebrew word is rendered "the dead," or "the shades" in various passages (Job 26:5 margin; Psalms 88:10 margin; Proverbs 2:18 margin; Proverbs 9:18 margin; Proverbs 21:16 margin; Isaiah 14:9 margin; Isaiah 26:14, Isaiah 26:19 margin). In these instances the word is derived from rapheh, "weak," "powerless," "a shadow" or "shade."
H. Porter