From Longman Dictionary of Contemporary Englishpadded cellˌpadded ˈcell noun [countable] MHMPa special room in a hospital for people who are mentally ill. The room has thick soft material on the walls so that the person in it cannot get hurt.
Examples from the Corpus
padded cell• Fulfilling her needs won't settle his, he shouldn't be kept in a padded cell.• He padded his bedroom - literally like a padded cell - so that he wouldn't hear the noise of traffic outside.• Adam was so extreme; they really would cart him off to a padded cell one of these days.• Away from what most other people would regard as glamour, he retreated to that padded cell off the Edgware Road. 