Synonyms for Infernal Region (same or very similar meaning)
WordNet sense 1 ((Christianity) the abode of Satan and the forces of evil; where sinners suffer eternal punishment):
hell, inferno, perdition, pit, nether regionWordNet sense 2 ((religion) the world of the dead):
netherworld, underworld, Hades, Hel, Scheol, hadesFrom the ODE community, based on WordNetadd/edit