A prisoner is someone who is being held in a place they cannot leave, usually as a punishment for breaking the law. When a judge sentences someone to time in prison, that person becomes a prisoner who must stay locked up for months or years. Prisons are secure buildings designed to keep prisoners inside while they serve their sentences.

The word also applies in other situations. During wartime, soldiers who are captured become prisoners of war, or POWs. These prisoners aren't criminals but are held by the enemy until the war ends. In stories and history, you might read about someone being taken prisoner by pirates or kidnappers, meaning they were captured and held against their will.

Sometimes people use prisoner more loosely to describe feeling trapped by circumstances. A student might say they feel like a prisoner during a boring assembly, though of course they can leave when it ends. A prisoner of fear is someone so afraid that they can't bring themselves to try new things. These uses show how the word captures that feeling of being stuck or confined, whether by actual walls and guards or by something else entirely.

The key element is loss of freedom: prisoners cannot go where they want, when they want. That's what makes imprisonment such a serious consequence.