A prisoner (of war): someone captured during conflict, especially in wartime; a captive or POW.
戦争で多くの捕虜が収容所に送られた。
Many prisoners of war were sent to detention camps during the war.
捕虜交換の交渉が始まったと報じられた。
It was reported that negotiations for a prisoner exchange had begun.
彼は敵に捕らえられ、捕虜として扱われた。
He was captured by the enemy and treated as a prisoner.