'Gehenna' definitions:

Definition of 'Gehenna'

noun

A place where the wicked are punished after death [syn: Gehenna, Tartarus]

From: GCIDE

Gehenna \Ge*hen"na\ (g[-e]*h[e^]n"n[.a]), prop. n. [L. Gehenna, Gr. Ge`enna, Heb. G[=e] Hinn[=o]m.] (Jewish Hist.) The valley of Hinnom, near Jerusalem, where some of the Israelites sacrificed their children to Moloch, which, on this account, was afterward regarded as a place of abomination, and made a receptacle for all the refuse of the city, perpetual fires being kept up in order to prevent pestilential effluvia. In the New Testament the name is transferred, by an easy metaphor, to Hell. [1913 Webster]
The pleasant valley of Hinnom. Tophet thence And black Gehenna called, the type of Hell. --Milton. [1913 Webster]

Gehenna (originally Ge bene Hinnom; i.e., "the valley of the sons of Hinnom"), a deep, narrow glen to the south of Jerusalem, where the idolatrous Jews offered their children in sacrifice to Molech (2 Chr. 28:3; 33:6; Jer. 7:31; 19:2-6). This valley afterwards became the common receptacle for all the refuse of the city. Here the dead bodies of animals and of criminals, and all kinds of filth, were cast and consumed by fire kept always burning. It thus in process of time became the image of the place of everlasting destruction. In this sense it is used by our Lord in Matt. 5:22, 29, 30; 10:28; 18:9; 23:15, 33; Mark 9:43, 45, 47; Luke 12:5. In these passages, and also in James 3:6, the word is uniformly rendered "hell," the Revised Version placing "Gehenna" in the margin. (See HELL; HINNOM.)