Synonyms of 'catastrophic'
disastrousDictionary, devastating, tragic
A tidal wave caused catastrophic damage.
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If you describe an event or situation as calamitous, you mean it is very unfortunate or serious.
a calamitous air crash
A cataclysmic event is one that changes a situation or society very greatly, especially in an unpleasant way.
Few had expected the change to be as cataclysmic as it was.
Thesaurus for catastrophic from the Collins English Thesaurus
Something that is catastrophic involves or causes a sudden terrible disaster .