Definition of "cataclysmal"

cataclysmal

adjective
comparative more cataclysmal, superlative most cataclysmal
1. As noisy or destructive as a cataclysm.
  Quotations
  That they have been exterminated by exceptional cataclysmal changes of the earth's surface has not been proved.
  1861, Richard Owen, Palaeontology Or A Systematic Summary of Extinct Animals and Their Geological Relations
  Perhaps she’s so deaf that nothing short of a cataclysmal uproar will reach her auditory nerves.
  1897, Richard Marsh, The Beetle