From Longman Dictionary of Contemporary Englishhang by a threadhang by a threadDANGEROUSif something is hanging by a thread, it is in a very dangerous situation and may not continue He is still in hospital, his life hanging by a thread. → hang
Examples from the Corpus
hang by a thread• Ed was just hanging by a thread.• Liputin's teeth are by no means the only things that hang by a thread.• His job is hanging by a thread, as it is.• Hopes of a title hat-trick hang by a thread, but all is not quite lost. 