den /den/ BrE AmE noun [countable]
[ Language: Old English ; Origin: denn ]
1 . the home of some animals, for example lions or ↑ fox es
2 . a place where secret or illegal activities take place:
corrupt gambling dens
a den of thieves
3 . an enclosed and secret place where children play
4 . especially American English a room in a house where people relax, watch television etc
5 . British English old-fashioned a small room in a house where people can work, read etc without being interrupted:
Father retreated to his den.
6 . den of iniquity 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.