> a place where large numbers of people, especially political prisoners or members of persecuted minorities, are deliberately imprisoned in a relatively small area with inadequate facilities, sometimes to provide forced labor or to await mass execution.
The most famous usage was by Germans and is heavily associated with extermination, but the British just wish to deprive the Boer’s of support and to put pressure on them into surrendering. Hence the term “concentration” rather than “extermination”. Many Boers did wind up dying due to inadequate sanitation and food, but the point wasn’t to kill them.
Whether the camps in Xinjiang are concentration camps or not remains to be seen. Definitely some of the awful work camps in China in the 70s met the threshold.