Other forms: prisoners
A prisoner is a person being held in prison as a punishment. During wartime a prisoner is someone held captive by the enemy. Alternately, if you’re so attractive you can’t leave the house, you’re a prisoner of your own good looks.
Someone who's caught robbing a bank or stealing a car will probably become a prisoner, locked inside a prison for as long as the sentence specifies. If you feel stuck or confined in some way, you may consider yourself a metaphorical prisoner, like an actor who whines that he’s a prisoner of his own success, since he’s not able to go anywhere without cameras flashing and fans screaming.