v. phr. To depend on a very small thing; be in doubt. For three days Tom was so sick that his life hung by a thread. As Joe got ready to kick a field goal, the result of the game hung by a hair.
Compare: HANG IN THE BALANCE.
HANG BY A THREAD
Meaning of HANG BY A THREAD in English
American idioms English vocabulary. Английский словарь американских идиом. 2012