den
/den; dɛn/ n
1 animal's hidden home, eg a cave 兽穴; 窝（如山洞）
a bear's/lion's den 熊的[狮子的]洞穴.
2 (derog 贬) secret meeting-place 秘密相聚之处
an `opium den 鸦片烟窟 * a den of thieves 贼窝.
3 (infml 口) room in a home where a person can work or study without being disturbed （家中的）私室, 书斋
retire to one's den 回到自己的私室.
4 (idm 习语) beard the lion in his den => beard2. a den of i`niquity/`vice (often joc 常作戏谑语) a place where evil or immoral activities go on 进行罪恶活动的地方
He thought of New York as a den of iniquity. 他认为纽约是个藏污纳垢之处.