(tsalmaweth): The Hebrew word translated "shadow of death" is used poetically for thick darkness (Job 3:5), as descriptive of Sheol (Job 10:21 f; Job 12:22; 38:17); figuratively of deep distress (Job 12:22; 16:16; 24:17 twice; Job 28:3; 34:22 (in the last three passages the American Standard Revised Version has "thick darkness" and "thick gloom"); Ps 23:4, the Revised Version margin "deep darkness (and so elsewhere)"; Ps 44:19; 107:10,14; Isa 9:2; Jer 2:6; 13:16; Am 5:8; Mt 4:16; Lu 1:79, skia thanatou). The Hebrew word is perhaps composed of tsel, "shadow," and maweth, "death," and the idea of "the valley of the shadow of death" was most probably derived from the deep ravines, darkened by over-hanging briars, etc., through which the shepherd had sometimes to lead or drive his sheep to new and better pastures.
W. L. Walker