Abbreviated form of
Gey Ben Hinnom, ‘Valley of Ben Hinnom’, a place where children were burned in fire in the worship of Molech (2 Kings 23: 10). Because of the association with burning in fire the name Gehinnom (or, from the Greek, Gehenna) became the name in post-biblical Judaism (and in the New Testament) for the place of torment of the wicked after death. Thus Gehinnom and its opposite Gan Eden are synonymous with heaven and hell.