SPECIAL TOPIC: BELIAL

This is a Hebrew term (i.e., beli and ya'al, see BDB 116) whose etymology is somewhat in doubt. Beliar is a variant spelling from some Jewish writings. The possible backgrounds are:

worthlessness (i.e., a description of evil people, cf. Deut. 13:13; 2 Sam. 23:6; 1 Kgs. 21:10,13)
lawlessness (cf. 2 Sam. 22:5)
place from where there is no ascent (i.e., Sheol, cf. Ps. 18:4)
another term for Satan (cf. Nahum 1:15; Jubilees 1:20; 15:33; and the Dead Sea Scrolls [ex. IQS 1:18,24; 2:5,19])