“The site for the last great battle between the forces of good and the forces of evil before the day of judgement (Revelations 16:16). The Hebrew word supposedly refers to Megiddo, which, in the history of Israel, was the scene of many great battles. The word has come to mean any great final struggle or conflict and is comparable to Ragnarok in Norse mythology.”
Excerpted from: Murphy, Bruce, ed. Benet’s Reader’s Encyclopedia, Fourth Edition. New York: Harper Collins, 1996.