From the Encylopaedia Judia
Ben-Hinnom, Valley of [the Son(s) of Hinnom, Gehenna) a
valley south of Jerusalem on one of the borders between
the territories of Judah and Benjamin, between the Valley
of Rephaim and En-Rogel (Josh. 15:8, 18:16). It is identified with
During the time of Monarchy, Gehinnom, at a place called Topheth, was the site of a cult which involved the burning of children (II Kings 23:10, Jer. 7:31 ; 32:35 et al; see Moloch). Jeremiah repeatedly rebuked this cult and predicted that on it's account Tophet and the Valley of the Son of Hinnom would be called the valley of the "slaughter" (Jer. 19:5-6)
In Judasim the name Gehinom is generally used metaphorically as an appellation for the place of torment reserved for the wicked after death. The New Testament uses the Greek from the Gehenna in the same sense.