the home of some animals, for example lions or foxes
a place where secret or illegal activities take place:
corrupt gambling dens
a den of thieves
an enclosed and secret place where children play
4 especially American EnglishDH
a room in a house where people relax, watch television etc
5DH British English old-fashioned
a small room in a house where people can work, read etc without being interrupted:
Father retreated to his den.
a place where activities that you think are immoral or evil happen - often used humorously:
Her mother was convinced that London was a den of iniquity.