Wiktionary
n. A thing or situation which causes a prolonged state of impending doom or misfortune.
WordNet
n. a constant and immanent peril; "the possibility hangs over their heads like the sword of Damocles"
Usage examples of "sword of damocles".
This data is extremely sensitive but right now all you have is the Sword of Damocles hanging over a few of your minor diplomats.
That was the People's Navy's most sensitive post, the one naval command perpetually poised above the Committee of Public Safety's head like some megaton Sword of Damocles.
For all those years, since Richelieu had been appointed head of the Royal Council, the king's childlessness had hovered over the cardinal like the proverbial Sword of Damocles.
I suppose one might argue under the circumstances that it would be courteous t' alert her t' the Sword of Damocles you've just suspended above her head.
It was like having a double-ended Sword of Damocles hanging over his head, and now, obviously, something about Terekhov bothered him deeply.
They lived under the sword of Damocles, knowing that it must fall.
This was a Sword of Damocles over both their heads, hanging by a thread.
For the first time, since the sword of Damocles had fallen, she was alone with her thoughts.