hang by a thread

1. Literally, to be attached only by single thread or strand or material. If that button is only hanging by a thread, you're bound to lose it during the course of the day. I bet she loses that tooth today—it's basically hanging by a thread at this point. Whoa, grab the wreath before it falls—it's only hanging by a thread!

2. To be perilously close to failing, dying, or resulting in a bad outcome. After the loss, their chances of getting into the championships are hanging by a thread. Her life hung by a thread as medics rushed her to the hospital. I'm warning you, Davis, you're hanging by a thread! One more slip up, and you're fired!

See also: by, hang, thread

hang by a thread

Also, hang by a hair. Be in a risky or unstable situation, as in His promotion was hanging by a thread, or With the lead actor sick, the success of our play hung by a hair. This expression, already proverbial in the early 1500s, alludes to Damocles, who vexed King Dionysius with constant flattery. The king invited him to a banquet where Damocles found himself seated under a naked sword suspended by a single hair, symbolizing his insecure position at the court.

See also: by, hang, thread

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

hang by a thread

1. If something hangs by a thread, it is very likely to fail, although it has not failed yet. It's clear that the ceasefire is hanging by a thread. England's World Cup hopes hang by a thread and they must now rely on the results of the others in their group going their way.

2. If someone's life hangs by a thread, they are seriously ill and are very likely to die. His kidneys had failed and his life was hanging by a thread. Note: This expression may relate to the story of the Sword of Damocles: see the explanation at `sword'.

See also: by, hang, thread

Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

hang by a thread

be in a highly precarious state.

See also: by, hang, thread

hang by a ˈthread/ˈhair

be in a very uncertain situation: After the operation, his life hung by a thread for several hours. ♢ The future of this company hangs by a thread. Unless we get two or three big orders by the end of the month, we’re finished.

hang by a thread, to

To be in a precarious situation. This expression comes from the story of Damocles, a servile courtier to Dionysius I of Syracuse. Tired of hearing Damocles praise him to the skies, Dionysius invited him to a magnificent banquet. Seated there, Damocles looked up and saw a naked sword suspended over his head by a single hair, whereby the king intended to show his servant the insecurity of his position. By the sixteenth century the story had been converted into a proverb, “It hangs by a hair,” listed in Erasmus’s Adagia (1523), and in the course of time hair was changed to thread.