Cataclysm :: Cataclysm (n.) An extensive overflow or sweeping flood of water; a deluge.
Cataclysm :: Cataclysm (n.) Any violent catastrophe, involving sudden and extensive changes of the earth's surface..
Cataclysmist :: Cataclysmist (n.) One who believes that the most important geological phenomena have been produced by cataclysms.
Clysmian :: Clysmian (a.) Connected with, or related to, the deluge, or to a cataclysm; as, clysmian changes..