Ge'he'nnom

Gehennom is the Hebrew word for Hell.
The origin of the word is from the Bible, it was a place where worshipers of moloch made human sacrifices.

Guy - The Hebrew word for valley.
Henom - Local ruler who worshiped moloch and owned the valley.

Gehennom is not mentioned in the bible as a place where sinners go after they die, that was only mentioned in later writings.
Modern use for the word: "sh'e tisaref ba gehennom" meaning "burn in hell"