Catastrophical

a sudden and widespread disaster:
the catastrophe of war.
any misfortune, mishap, or failure; fiasco:
The play was so poor our whole evening was a catastrophe.
a final event or conclusion, usually an unfortunate one; a disastrous end:
the great catastrophe of the Old South at Appomattox.
(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 catastrophe function. Mathematics. any of the mathematical functions that describe the discontinuities that are treated in catastrophe theory.
of the nature of a catastrophe, or disastrous event; calamitous:
a catastrophic failure of the dam.
Historical Examples

At seventeen such things are not embarrassing; they are catastrophical.
Seventeen Booth Tarkington

noun
a sudden, extensive, or notable disaster or misfortune
the denouement of a play, esp a classical tragedy
a final decisive event, usually causing a disastrous end
Also called cataclysm. any sudden and violent change in the earth’s surface caused by flooding, earthquake, or some other rapid process
adj.

1824, from catastrophe + -ic. Related: Catastrophical; catastrophically.
n.

1530s, “reversal of what is expected” (especially a fatal turning point in a drama), from Latin catastropha, from Greek katastrophe “an overturning; a sudden end,” from katastrephein “to overturn, turn down, trample on; to come to an end,” from kata “down” (see cata-) + strephein “turn” (see strophe). Extension to “sudden disaster” is first recorded 1748.