Armageddon in the Bible.

About Armageddon.

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.).

From Easton’s Bible Dictionary (1897).