One is faced with imminent danger or trouble. In Greek mythology, the courtier Damocles was forced to sit beneath a sword suspended by a single hair to emphasize the instability of a king's fortunes. I know how irritable and unpredictable the boss can be, so I feel like Damocles' sword hangs over me whenever I'm alone with him. With the threat of nuclear war, many feel that Damocles' sword is hanging over the entire world.