cataclysm
/ˈkætəklɪzəm/noun
1- a large-scale and violent event in the natural world（自然界的）剧变, 大变化。
1.1
- a sudden violent upheaval, especially in a political or social context（尤指政治或社会方面的）大动乱, 大变革：
the cataclysm of the First World War.
第一次世界大战的大灾难。
词源
early 17th cent. (originally denoting the biblical Flood described in Genesis)： from French cataclysme, via Latin from Greek kataklusmos 'deluge', from kata- 'down' + kluzein 'to wash'.