If you describe an event or situation as calamitous, you mean it is very unfortunate or serious.
例句
...the calamitous state of the country.国势危难...a calamitous air crash.一起严重的坠机事件
英汉词典释义
adj.
灾难的;悲惨的
a calamitous mistake灾难性的错误
英英词典释义
Adjective
1. (of events) having extremely unfortunate or dire consequences; bringing ruin;
"the stock market crashed on Black Friday""a calamitous defeat""the battle was a disastrous end to a disastrous campaign""such doctrines, if true, would be absolutely fatal to my theory"- Charles Darwin"it is fatal to enter any war without the will to win it"- Douglas MacArthur"a fateful error"