the hidden home of some types of wild animal 兽穴；兽窝 a bear’s/lion’s den 熊的／狮子的洞穴
- (disapproving)
a place where people meet in secret, especially for some illegal activity 窝点，窝子（尤指非法或邪恶活动秘密聚会处） a den of thieves 贼窝 a drinking/gambling den 酗酒窝点；赌窟 He thought of New York as a den of iniquity. 他把纽约视为罪恶的渊薮。
- (North American English)
a room in a house where people go to relax, watch television, etc. 休息室 - (British English, old-fashioned, informal)
a room in a house where a person can work or study without being interrupted 书斋；书房 a secret place, often made roughly with walls and a roof, where children play （儿童的）隐蔽玩耍处 - (North American English)
a group of Cub Scouts 书房： 一组幼童军
Word OriginOld English denn, of Germanic origin; related to German Tenne ‘threshing floor’, also to dene ‘vale’.
Idioms
the lion’s den
a difficult situation in which you have to face a person or people who are unfriendly or aggressive towards you 龙潭虎穴
to beard the lion in his den
to go to see an important or powerful person to tell them that you disagree with them, that you want something, etc. 进狮穴捋狮须（敢于触犯有权势者）