A place where a tyrranical goverment sends a group (or groups) of people that the leader/leaders of the tyrrany doesn't/don't like. Often times, it is a closed-off area that is surrounded by barbed-wire fences and search towers. The main reason that the tyrannical government sends these people to the camps is because they want them killed off because they think that that particular group of people is inferior or a danger to society. Not many people survive these camps.
"My grandfather was sent to a German concentration camp because he was Jewish. He's one of the lucky Holocaust survivors."