used to refer to a precarious situation达摩克利斯之剑；临头的危险
柯林斯高阶英汉双解学习词典释义
PHRASE
达摩克利斯之剑;随时可能发生的危险
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.
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)