apocalypse
noun
definition 1: any of several early Jewish or Christian writings on divine revelation that symbolically depict the ultimate conflict between good and evil.
definition 2: (cap.) the last book of the New Testament, ascribed to St. John the Divine; the Book of Revelation; Revelations.
definition 3: any instance of terrible destruction and devastation, especially on a scale that would bring about an end to the world.
example: Nuclear war in the region could lead to an apocalypse.