|Easton's Bible Dictionary|
The broken or divided place, a district in the Arabah or Jordan valley, on the east of the river (2 Samuel 2:29). It was probably the designation of the region in general, which is broken and intersected by ravines.
Int. Standard Bible Encyclopedia
bith'-ron (ha-bithron; holen ten parateinousan, literally "the entire (land) extending"; 2 Samuel 2:29, "the Bithron," i.e. the gorge or groove): Does not seem to be a proper name; rather it indicates the gorge by which Abner approached Mahanaim. Buhl (GAP, 121) favors identification with Wady `Ajlun, along which in later times a Roman road connected `Ajlun and Mahanaim. Others (Guthe, Kurz. bib. Worterbuch, under the word) incline to Wady esh Sha`ib.
Bithron (1 Occurrence)
2 Samuel 2:29 Abner and his men went all that night through the Arabah; and they passed over the Jordan, and went through all Bithron, and came to Mahanaim. (WEB KJV JPS ASV BBE DBY WBS YLT NIV)