"Occurs only in Rev. 16:16 (R.V., "Har-Magedon"), as symbolically" "designating the place where the "battle of that great day of God" "Almighty" (ver. 14) shall be fought. The word properly means the" mount of Megiddo. It is the scene of the final conflict between Christ and Antichrist. The idea of such a scene was "suggested by the Old Testament great battle-field, the plain of" Esdraelon (q.v.).

See where Armageddon occurs in the Bible...

Definition of Armageddon:
"hill of fruits; mountain of Megiddo"