SPECIAL TOPIC: REPHAIM (BDB 952, KB 1274-5)

This root has at least two usages in the OT.

a race of giants (BDB 752, see SPECIAL TOPIC: sons of God in Genesis 6), mentioned in Gen. 14:5; 15:20; Deut. 2:10-11,20; 3:11; Josh. 12:4; 17:15; 1 Chr. 20:4,6,8 (also possibly 2 Sam. 2:16,18,20,22)
The Rephaim are put in a parallel relationship to (cf. Deut. 2:10-11,20)
1. Emim (BDB 34)
2. Zamzummin (BDB 273)
3. Anakim (BDB 778)
a designation for the dead (shades or ghosts) now powerless in Sheol, but conscious, cf. Job 26:5-6; Ps. 88:10; Prov. 2:18; 9:18; 21:16; Isa. 14:9; 26:11-19
For a good discussion of the possible connotations of this root, see NIDOTTE, vol. 3, pp. 1173-1180.
KB 1274 suggests the root (BDB 952) is related to BDB 950, "heal" and therefore, to an ancient guild/race of "healers."