What is "topheth"

Tophet \To"phet\, n. [Heb. t[=o]phet, literally, a place to be spit upon, an abominable place, fr. t[=u]ph to spit out.] A place lying east or southeast of Jerusalem, in the valley of Hinnom. [Written also Topheth.]

And he defiled Topheth, which is in the valley of the children of Hinnom.
--2 Kings xxiii. 10.

Note: It seems to have been at first part of the royal garden, but it was afterwards defiled and polluted by the sacrifices of Baal and the fires of Moloch, and resounded with the cries of burning infants. At a later period, its altars and high places were thrown down, and all the filth of the city poured into it, until it became the abhorrence of Jerusalem, and, in symbol, the place where are wailing and gnashing of teeth.

The pleasant valley of Hinnom, Tophet thence And black Gehenna called, the type of hell.
--Milton.