The word APOCALYPSE or ARMAGEDDON is derived from 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.' Down through history, however, the word's meaning has be altered to refer to the cataclysmic events soon to come upon the earth before the return of Christ that are described in the book of Revelation. The words, therefore, are another way of referencing the prophetic last book of the Bible.
The word Apocalypse can also be used technically to apply to a particular king of Biblical prophecy. Apocalyptic verses in God's word are viewed as foretelling events that MUST 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 - Revelation 16:12-16.)
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:
7 Joshua and the people of Israel defeated all the kings in the territory west of the Jordan, from Baalgad in the valley of Lebanon to Mount Halak in the south near Edom . . . 9 The people of Israel defeated the kings of the following cities . . . 21 Taanach, Megiddo (Joshua 12)
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).