A catastrophe is a disaster. If a wedding reception is disrupted by a fistfight between the bride and her new mother-in-law, you could call the occasion a catastrophe.

Catastrophe comes from a Greek word meaning "overturn." It originally referred to the disastrous finish of a drama, usually a tragedy. The definition was extended to mean "any sudden disaster" in the 1700s. Nowadays, catastrophe can be used to refer to very tragic events as well as more minor ones. A hurricane destroying hundreds of homes is certainly a catastrophe; baking a birthday cake without following a recipe might also result in catastrophe, if you don't know anything about cooking.

Definitions of catastrophe

n a sudden violent change in the earth's surface

nuclear winter
a long period of darkness and extreme cold that scientists predict would follow a full-scale nuclear war; a layer of dust and smoke in the atmosphere would cover the earth and block the rays of the sun; most living organisms would perish
Type of:
geological phenomenon
a natural phenomenon involving the structure or composition of the earth

n an event resulting in great loss and misfortune

calamity, cataclysm, disaster, tragedy
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act of God, force majeure, inevitable accident, unavoidable casualty, vis major
a natural and unavoidable catastrophe that interrupts the expected course of events
a cosmic cataclysm in which God destroys the ruling powers of evil
a severe shortage of food (as through crop failure) resulting in violent hunger and starvation and death
kiss of death
something that is ruinous
a disaster comparable to a nuclear meltdown
any large scale calamity (especially when thought to be sent by God)
any disaster or catastrophe
tidal wave
an unusual (and often destructive) rise of water along the seashore caused by a storm or a combination of wind and high tide
a cataclysm resulting from a destructive sea wave caused by an earthquake or volcanic eruption
the Great Calamity, the Great Hunger, the Great Starvation, the Irish Famine
a famine in Ireland resulting from a potato blight; between 1846 and 1851 a million people starved to death and 1.6 million emigrated (most to America)
Type of:
bad luck, misfortune
unnecessary and unforeseen trouble resulting from an unfortunate event

n a state of extreme (usually irremediable) ruin and misfortune

“lack of funds has resulted in a catastrophe for our school system”
Type of:
adversity, hard knocks, hardship
a state of misfortune or affliction