A nasty, licentious, obscene fellow. Bel-Phegor was a Moabitish deity, whose rites were celebrated on Mount Phegor, and were noted for their obscenity. The Standard, speaking of certain museums in London, says, “When will men cease to be deluded by these unscrupulous Belphegors?” (meaning “quacks”).
Phegor, Phogor, or Peor, a famous mountain beyond the Jordan. Nebo and Pisgah were neighbouring mountains. Beth-Peor is referred to in Deut. iii. 29.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894