apoc·a·lypse
 /əˈpɑːkəˌlıps/  noun   [  singular  ]
  : a great disaster : a sudden and very bad event that causes much fear, loss, or destruction
   His book tells of an environmental apocalypse.
   fears of a nuclear apocalypse [=a disaster caused by nuclear weapons]
  the apocalypse
   : the end or destruction of the world especially as described in the Christian Bible
    Some people believed the apocalypse would happen in the year 2000.
    waiting for the apocalypse