used to refer to a precarious situation達摩克利斯之劍；臨頭的危險
柯林斯高階英漢雙解學習詞典釋義
PHRASE
達摩克利斯之劍;隨時可能發生的危險
If you say that someone has the Sword of Damocles hanging over their head, you mean that they are in a situation in which something very bad could happen to them at any time.
例句
As a Grand Prix driver, you have the Sword of Damocles hanging over your head at every moment.作為國際汽車大獎賽的車手，隨時都有可能發生事故。
英英詞典釋義
Noun
1. the Greek courtier to Dionysius the Elder who (according to legend) was condemned to sit under a naked sword that was suspended by a hair in order to demonstrate to him that being a king was not the happy state Damocles had said it was (4th century BC)