catastrophe

a sudden and widespread disaster:

any misfortune, mishap, or failure; fiasco:

a final event or conclusion, usually an unfortunate one; a disastrous end:

(in a drama) the point at which the circumstances overcome the central motive, introducing the close or conclusion; dénouement. Compare catastasis, epitasis, protasis.

Geology. a sudden, violent disturbance, especially of a part of the surface of the earth; cataclysm.

Also called ca·tas·tro·phe func·tion [k, uh, -, tas, -tr, uh, -fee fuhngk-sh, uh, n]. Mathematics. any of the mathematical functions that describe the discontinuities that are treated in catastrophe theory.