“Hinnom” means lamentation

Hinnom: , Valley of, otherwise called "the valley of the son" or "children of Hinnom," a deep and narrow ravine, with steep, rocky sides, to the south and west of Jerusalem, separating Mount Zion to the north from the "hill of evil counsel," and the sloping rocky plateau of the "plain of Rephaim" to the south. The earliest mention of the valley of Hinnom is in (Joshua 15:8; 18:16) where the boundary line between the tribes of Judah and Benjamin is described as passing along the bed of the ravine. On the southern brow, overlooking the valley at its eastern extremity Solomon erected high places for Molech, (1 Kings 11:7) whose horrid rites were revived from time to time in the same vicinity the later idolatrous kings. Ahaz and Manasseh made their children "pass through the fire" in this valley, (2 Kings 16:3; 2 Chronicles 28:3; 33:6) and the fiendish custom of infant sacrifice to the fire-gods seems to have been kept up in Tophet, which was another name for this place. To put an end to these abominations the place was polluted by Josiah, who renders it ceremonially unclean by spreading over it human bones and other corruptions, (2 Kings 23:10,13,14; 2 Chronicles 34:4,5) from which time it appears to have become the common cesspool of the city, into which sewage was conducted, to be carried off by the waters of the Kidron. From its ceremonial defilement, and from the detested and abominable fire of Molech, if not from the supposed ever-burning funeral piles, the later Jews applied the name of this valley --Ge Hinnom, Gehenna (land of Hinnom)--to denote the place of eternal torment. In this sense the word is used by our Lord. (Matthew 5:29; 10:28; 23:15; Mark 9:43; Luke 12:5)