CATACLASM
Cat"a*clasm, n. [Gr. ; down + to break.]

Defn: A breaking asunder; disruption.

CATACLYSM
Cat"a*clysm, n. Etym: [L. cataclysmos, Gr. cataclysme.]

1. An extensive overflow or sweeping flood of water; a deluge.

2. (Geol.)

Defn: Any violent catastrophe, involving sudden and extensive changes of the earth's surface.

CATACLYSMAL; CATACLYSMIC
Cat`a*clys"mal, Cat"a*clys"mic, a.

Defn: Of or pertaining to a cataclysm.

CATACLYSMIST
Cat`a*clys"mist, n.

Defn: One who believes that the most important geological phenomena have been produced by cataclysms.