ˈknife-edge BrE AmE noun [singular]
1 . a situation in which the result is extremely uncertain
on a knife-edge
His future in the job is balanced on a knife-edge.
a knife-edge vote
2 . a situation which makes someone very anxious
on a knife-edge
Living with him, she is constantly on a knife-edge.
the knife-edge of insecurity
3 . something that is narrow or sharp