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[Judaic] Ancient Syrian and Phoenician chthonic beings, associated with fertility and the underworld. The name is also given to a race of semi-divine heroes, giants, who once lived in Canaan. These were the offspring of the sons of God and the daughters of men (Gen. vi, 4).

Rephaim repha'im (Hebrew) The sons of Raphah, a Canaanite race of giants; also the weak ones, shades or specters, the quiet and wan inhabitants of Hades or the Underworld, which were nevertheless considered beings of gigantic size, and hence the collocation of the meanings of gigantic magnitude coupled with intrinsic weakness. This last refers to the phantom or astral races of early mankind: the first, second, and early third root-races before they were illuminated and inspired by the manasaputric descent (SD 2:279).
The passage in Job (26:5) translated "Dead things are formed from under the waters, and the inhabitants thereof," should be "dead rephaim."

See: Giants
  

lofty men; giants, (Gen. 14:5; 2 Sam. 21:16, 18, marg. A.V., Rapha, marg. R.V., Raphah; Deut. 3:13, R.V.; A.V., "giants"). The aborigines of Palestine, afterwards conquered and dispossessed by the Canaanite tribes, are classed under this general title. They were known to the Moabites as Emim, i.e., "fearful", (Deut. 2:11), and to the Ammonites as Zamzummim. Some of them found refuge among the Philistines, and were still existing in the days of David. We know nothing of their origin. They were not necessarily connected with the "giants" (R.V., "Nephilim") of Gen. 6:4. (See GIANTS.)

(Josh. 15:8; 18:16, R.V.). When David became king over all Israel, the Philistines, judging that he would now become their uncompromising enemy, made a sudden attack upon Hebron, compelling David to retire from it. He sought refuge in "the hold" at Adullam (2 Sam. 5:17-22), and the Philistines took up their position in the valley of Rephaim, on the west and south-west of Jerusalem. Thus all communication between Bethlehem and Jerusalem was intercepted. While David and his army were encamped here, there occurred that incident narrated in 2 Sam. 23:15-17. Having obtained divine direction, David led his army against the Philistines, and gained a complete victory over them. The scene of this victory was afterwards called Baalperazim (q.v.). A second time, however, the Philistines rallied their forces in this valley (2 Sam. 5:22). Again warned by a divine oracle, David led his army to Gibeon, and attacked the Philistines from the south, inflicting on them another severe defeat, and chasing them with great slaughter to Gezer (q.v.). There David kept in check these enemies of Israel. This valley is now called el-Bukei'a.

See more at Wikipedia.org...

[Judaic] Ancient Syrian and Phoenician chthonic beings, associated with fertility and the underworld. The name is also given to a race of semi-divine heroes, giants, who once lived in Canaan. These were the offspring of the sons of God and the daughters of men (Gen. vi, 4).

Rephaim repha'im (Hebrew) The sons of Raphah, a Canaanite race of giants; also the weak ones, shades or specters, the quiet and wan inhabitants of Hades or the Underworld, which were nevertheless considered beings of gigantic size, and hence the collocation of the meanings of gigantic magnitude coupled with intrinsic weakness. This last refers to the phantom or astral races of early mankind: the first, second, and early third root-races before they were illuminated and inspired by the manasaputric descent (SD 2:279).
The passage in Job (26:5) translated "Dead things are formed from under the waters, and the inhabitants thereof," should be "dead rephaim."

See: Giants
  

lofty men; giants, (Gen. 14:5; 2 Sam. 21:16, 18, marg. A.V., Rapha, marg. R.V., Raphah; Deut. 3:13, R.V.; A.V., "giants"). The aborigines of Palestine, afterwards conquered and dispossessed by the Canaanite tribes, are classed under this general title. They were known to the Moabites as Emim, i.e., "fearful", (Deut. 2:11), and to the Ammonites as Zamzummim. Some of them found refuge among the Philistines, and were still existing in the days of David. We know nothing of their origin. They were not necessarily connected with the "giants" (R.V., "Nephilim") of Gen. 6:4. (See GIANTS.)

(Josh. 15:8; 18:16, R.V.). When David became king over all Israel, the Philistines, judging that he would now become their uncompromising enemy, made a sudden attack upon Hebron, compelling David to retire from it. He sought refuge in "the hold" at Adullam (2 Sam. 5:17-22), and the Philistines took up their position in the valley of Rephaim, on the west and south-west of Jerusalem. Thus all communication between Bethlehem and Jerusalem was intercepted. While David and his army were encamped here, there occurred that incident narrated in 2 Sam. 23:15-17. Having obtained divine direction, David led his army against the Philistines, and gained a complete victory over them. The scene of this victory was afterwards called Baalperazim (q.v.). A second time, however, the Philistines rallied their forces in this valley (2 Sam. 5:22). Again warned by a divine oracle, David led his army to Gibeon, and attacked the Philistines from the south, inflicting on them another severe defeat, and chasing them with great slaughter to Gezer (q.v.). There David kept in check these enemies of Israel. This valley is now called el-Bukei'a.