knife-edge >> ˈnʌɪfɛdʒ
Definition: [noun] the edge of a knife.
Definition: [noun] a very tense or dangerous situation.
Example: worried investors could be living on a knife-edge for the next twelve months
Definition: [noun] a sharp mountain ridge; an arête.
Definition: [noun] a steel wedge on which a pendulum or other device oscillates or is balanced.