In Christianapocalyptic literature (the Book of Revelation), Armageddon or Har-Mageddon is the site of the final battle between the kings of the earth (incited by Satan) and the Christian God. The term is also used for the battle itself, or more broadly for an Apocalypse.
The word armageddon is derived from Mount (Har in Hebrew) Megiddo, the site of the Battle of Megiddo and other battles. Armageddon in Christianity is also anticipated as the final battle between the forces of good (Jesus and his angels) and the forces of evil (Satan and his demons) (see also Dualism). It is the time of final judgement for the wicked humans of earth and the salvation for the just and good humans of earth. It is known as the final purification of the Earth's sin.
"Armageddon" also refers to any great loss of life in battle etc.
Armageddon was also the site for two great tragedies: the death of Saul and his sons (1 Samuel 31:8) and the death of King Josiah (2 Kings 23:29-30; 2 Chronicles 35:22).
The word Armageddon only occurs in Revelation 16:16, “Then they gathered the kings together to the place that in Hebrew is called Armageddon.” This speaks of the kings who are loyal to the Antichrist gathering together for a final assault on Israel.
Armageddon has become a general term that refers to the end of the world, not exclusively the battle that takes place in the Plain of Megiddo.