The word APOCALYPSE or ARMAGEDDON is one of several English translations of the Greek word apokalupsis (Strong's Concordance #G602). In many Bible translations (such as the New King James Translation used for the above verse) this Greek word, which means "disclosure, appearing, manifestation, be revealed, etc." is translated as Revelation. It has historically, however, taken on the meaning of "the horrible events foretold to happen at the end of Man's rule on Earth" which are described in the book of Revelation. Thus, it is another term for the book of Revelation, as well as the series of events described therein.
Apocalypse is also a technical term for a certain type of Biblical prophecy. An apocalyptic passage in the Bible is viewed as a prophecy describing events that will surely come to pass, and thus cannot be affected by the choices made by men. ARMAGEDDON, as opposed to its counterpart apocalypse, is frequently used as a term to label the entire time period starting from when the armies of the world begin to gather together (along with the beast and false prophet) to FIGHT Jesus to his actual return and victorious war over the forces of evil. It is after this victory that Christ sets up His Millennial Kingdom on the earth. The word armageddon, which means "mount of Megiddo," occurs only once in the Bible. Mount Megiddo itself is a small hill, located in the northern part of modern-day Israel, on which ancient forts were built that guarded the main highway, the Via Maris, that connected Ancient Egypt with Mesopotamia.
In the sixteenth chapter of Revelation the word is used to designate the location of the final, climactic battle between good (Jesus) and evil (the Antichrist) which will occur when Jesus returns to earth (known as the Second Coming):
"Then the sixth angel poured out his bowl on the great river Euphrates, and its water was dried up, so that the way of the kings from the east might be prepared . . . For they are spirits of demons, performing signs, which go out to the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty . . . And they gathered them together to the place called in Hebrew, ARMAGEDDON." (Revelation 16:12, 14,16, NKJV)
The valley and town of Megiddo belonged to Manasseh, one of the twelve tribes of Israel. Megiddo had been originally one of the royal cities of the Canaanites:
"And these are the kings of the country which Joshua and the children of Israel conquered on this side of the Jordan, on the west, from Baal Gad in the Valley of Lebanon as far as Mount Halak and the ascent to Seir, which Joshua gave to the tribes of Israel as a possession according to their divisions . . . the king of Taanach, one; the king of Megiddo, one;" (Joshua 12:7, 21)
It was one of the cities the Israelites, after entering the promised land of Palestine God gave them, were unable to take possession of for a long time. Megiddo was eventually taken over and during the reign of King Solomon was rebuilt and fortified (see 1Kings 4:12, 9:15).