1.An event producing a subversion of the order or system of things; a final event, usually of a calamitous or disastrous nature; hence, sudden calamity; great misfortune. "The strange catastrophe of affairs now at London." "The most horrible and portentous catastrophe that nature ever yet saw."
2.The final event in a romance or a dramatic piece; a denouement, as a death in a tragedy, or a marriage in a comedy.
3.(Geol.) A violent and widely extended change in the surface of the earth, as, an elevation or subsidence of some part of it, effected by internal causes.
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