What does hanging by a thread mean?

Answer 1

A thread is very thin and fragile, so if you're "hanging by a thread" you are in danger of breaking the thread and falling into whatever trouble is waiting.
The expression "Hanging on by a thread" means that the person has avoided danger or persecution by the narrowest of means, and is "holding on" the the very edge of safety ( the string represents safety from falling).
It means that what they're holding onto in the relationship and what would support them to stay and try and make it work--is just barely the strength and circumference of a single strand of thread. In other words, very, very little.

Answer 2

This is not really an idiom. Think about what something would be like if it was hanging onto something by a piece of thread. It wouldn't be very secure, would it? Hanging by a thread means barely hanging on, almost falling. T

Answer 3

It would mean to be hanged with a thread - however, the idiom HANGING BY A THREAD means that something is barely hanging on and is in danger of losing its grip. You would say "I am hanging by a thread" if you were in danger of failing a class, for example.