cataclysmic Syllabification: (cat·a·clys·mic)Pronunciation: /ˌkatəˈklizmik/Definition of cataclysmic adjective relating to or denoting a violent natural event. informal used to emphasize the extent of something bad or unwelcome:the concert was a cataclysmic failureDerivatives cataclysmicallyPronunciation: /-mik(ə)lē/ adverb cataclysmic in other Oxford dictionaries Definition of cataclysmic in the British & World English dictionary