Baal-peor

lord of the opening, a god of the Moabites (Num 25:3; 31:16; Josh 22:17), worshipped by obscene rites. So called from Mount Peor, where this worship was celebrated, the Baal of Peor. The Israelites fell into the worship of this idol (Num 25:3; 25:5; 25:18; Deut 4:3; Ps 106:28; Hos 9:10).

EBD - Easton's Bible Dictionary