Easton's Bible Dictionary (1897)
Swift, the southern boundary of the territory of Israel beyond Jordan, separating it from the land of Moab (Deut. 3:8, 16). This river (referred to twenty-four times in the Bible) rises in the mountains of Gilead, and after a circuitous course of about 80 miles through a deep ravine it falls into the Dead Sea nearly opposite Engedi. The stream is almost dry in summer. It is now called el-Mujeb. The territory of the Amorites extended from the Arnon to the Jabbok.
Smith's Bible Dictionary (1863)
(roaring), the river or torrent which formed the boundary between Moab and the Amorites, on the north of Moab, (Numbers 21:13,14,24,26; Judges 11:22) and afterwards between Moab and Israel (Reuben). (2:24,36; 3:8,12,16; 4:48; Joshua 12:1,2; 13:9,16; Judges 11:13,26) There can be no doubt that the Wady el-Mojeb of the present day is the Arnon. Its principal source is near Katrane, on the Haj route.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
AR'NON (noisy), a stream running into the Dead Sea from the east, and which divided Moab from the Ambrites. Num 21:13; Jud 11:18. The Arnon is about 50 miles long; 90 feet wide, and from 4 to 10 feet deep at its mouth; full in winter, but nearly dry in summer; had several fords, Isa 16:2, and "high places," Num 21:28; Isa 15:2; is referred to 24 times in the Bible. Its modern name is el-Mejib. It runs through a deep ravine with precipitous limestone cliffs on either side, in some places over 2000 feet high.
Ruins of forts, bridges, and buildings abound on its banks, and fish in its waters; oleanders and almond trees bloom in its valley, and griffons and buzzards may be seen hovering over its cliff's.
Hitchcock's Bible Names (1869)
rejoicing; sunlight