apocalypse

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Bible The Book of Revelation.
• noun Any of a number of anonymous Jewish or Christian texts from around the second century BC to the second century AD containing prophetic or symbolic visions, especially of the imminent destruction of the world and the salvation of the righteous.
• noun The end of the world, especially as described in one of these texts.
• noun A great catastrophe that results in widespread destruction or the collapse of civilization.
• noun A prophetic disclosure; a revelation.

from The Century Dictionary.

• noun Revelation; discovery; disclosure; specifically (with a capital letter), a title of the last book of the New Testament, usually called the book of Revelation, and in the English version the Revelation of St. John the Divine.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Eccl.) One of a numerous class of writings proceeding from Jewish authors between 250 b. c. and 150 a. d., and designed to propagate the Jewish faith or to cheer the hearts of the Jewish people with the promise of deliverance and glory; or proceeding from Christian authors of the opening centuries and designed to portray the future.
• noun Specifically, the revelation delivered to St. John, in the isle of Patmos, near the close of the first century, forming the last book of the New Testament (called Revelation or the Apocalypse).
• noun Anything viewed as a revelation, especially one that is highly significant for the person receiving it; a disclosure. Often used of a realization or revelation that changes a person's goals or style of life.
• noun the final battle between good and evil, as foreseen in Saint John's Apocalypse; the time when God conquers the powers of evil, attended by cataclysmic cosmic events, and sometimes thought of as the end of the world; an Armageddon.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a cosmic cataclysm in which God destroys the ruling powers of evil
• noun the last book of the New Testament; contains visionary descriptions of heaven and of conflicts between good and evil and of the end of the world; attributed to Saint John the Apostle