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.國勢危難...a calamitous air crash.一起嚴重的墜機事件
英漢詞典釋義
adj.
災難的;悲慘的
a calamitous mistake災難性的錯誤
英英詞典釋義
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"