1. 囚犯；犯人
    A prisoner is a person who is kept in a prison as a punishment for a crime that they have committed.

    e.g. The committee is concerned about the large number of prisoners sharing cells.
           这个委员会对牢房拥挤问题表示担忧。

2. 俘虏；战俘
    A prisoner is a person who has been captured by an enemy, for example in war.

prisoner在线翻译

    e.g. ...wartime hostages and concentration-camp prisoners...
           战时的人质和集中营的战俘
    e.g. He was held prisoner in Vietnam from 1966 to 1973...
           他在1966年到1973年间被作为战俘关押在越南。

3. 为…所困的人；陷于…不能摆脱的人
    If you say that you are a prisoner of a situation, you mean that your are trapped by it.

    e.g. We are all prisoners of our childhood and feel an obligation to it...
           我们都无法忘记自己的童年时代，觉得仍然为它所缚。
    e.g. She was a prisoner of her own ego.
           她为自己的自尊心所困。