IPA: /ˌkætəˈklɪzməl/
KK: /kætəˈklɪzməl/
Extremely destructive or disastrous, similar to a major catastrophe.
The earthquake had cataclysmal effects on the city, leaving many buildings in ruins.
Cataclysmal is formed from "cataclysm" (from Greek "kataklysmos", meaning a flood or deluge) and the suffix "-al" (meaning pertaining to). The word describes something that is related to or characteristic of a cataclysm, often implying a disastrous or violent event.
Think of a 'flood' or 'deluge' ('kataklysmos') that causes great destruction, and remember that 'cataclysmal' refers to something related to such a disastrous event.
No commonly confused words.