1) (kept as) a prisoner (captive)
2) a person who takes another person prisoner (captor)
3) chains for a prisoner (fetter)
4) a number of workmen or prisoner working together; a group of criminals (gang)
5) to save (a person, thing) (from danger, disaster, attack, being held prisoner etc) (rescue)
a person convicted of crime and being punished
criminal
a person against whom a legal action is brought
accused
a person kept as a guarantee that demands will be met
person held captive until captor's demand is met
a person living in a prison or other institution
patient