"Place of Torment." The Valley of Hinnom, south-west of Jerusalem, where Solomon, king of Israel, built "a high place", or place of worship, for the gods Chemosh and Moloch. The valley came to be regarded as a place of abomination because some of the Israelites sacrificed their children to Moloch there. In a later period it was made a refuse dump and perpetual fires were maintained there to prevent pestilence. Thus, in the New Testament, Gehenna became synonymous with hell.
See 1 Kings 11:7, and 2 Kings 23:10