hang (on) by a hair

hang (on) by a hair

1. Literally, to be attached only by something very thin and precarious. If that button is only hanging by a thread, you're bound to lose it during the course of the day.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 on by a thread. Her life hung by a thread as medics rushed her to the hospital.See also: by, hair, hang

hang by a hair

 and hang by a thread 1. Lit. to hang by something very thin, such as a thread or a hair. The tiniest part of the mobile hung by a thread, the rest are on plastic cords. 2. and hang on by a hair; hang on by a thread Fig. to depend on something very insubstantial; to hang in the balance. Your whole argument is hanging by a thread. John isn't failing geometry, but his passing grade is just hanging by a hair.See also: by, hair, hang