This word only lives in one phrase: **on tenterhooks**. It means you are waiting for news, and the waiting is doing something to you — you cannot settle, you cannot think about anything else, and it is not quite fear and not quite excitement. It is the feeling in the minutes before the exam results come out, or while the doctor is reading your test paper and has not said anything yet. Notice that the feeling is always about something not yet known. You are not on tenterhooks about a thing that already happened; you are on tenterhooks *until* you find out. Usually you say someone is on tenterhooks, or you keep / leave someone on tenterhooks — that means you know the answer and you are being slow about telling them, which is a small cruelty and people say it half-jokingly: "Don't keep me on tenterhooks — did you get the job?" It is a slightly bookish phrase, more common in writing and in older or more educated speech than in everyday teenage talk; a young person is more likely to say "I'm so nervous" or "the suspense is killing me". You will almost never meet the word alone. Nobody sells a tenterhook, and if you tried to use one tenterhook in a sentence it would sound wrong.

坐立不安、忐忑不安（等消息時的那種）。常見說法 on tenterhooks，中文比較接近「心懸著」「等到快抓狂」。注意這是「還沒揭曉」時的緊張，不是事後的擔心。