knife-edge /ˈnaɪfedʒ/ n. 1. 刀刃，锋刃 2. 极其锋利的东西 3. (天平等的)刃形支承 4. 陡峭的山脊，刃岭 5. 摇摆不定的处境；极微妙状态；十分焦急状态 be balanced on the knife-edge of agonizing decisions 处于非作出痛苦决定不可而又举棋不定的境地 The success or failure of the plan was balanced on a knife-edge. 计划的成败尚未定局。 be on a knife-edge about the examinations 对考试感到忐忑不安