underworld
/ˈʌndəwɜ:ld; `ʌndɚˌwəld/ n
the underworld [sing]
1 (in mythology) place under the earth inhabited by the departed spirits of the dead （神话中的）阴间, 阴曹.
2 part of society that lives by vice and crime 下流社会; 黑社会
police contacts in the London underworld伦敦黑社会中的警方眼线
[attrib 作定语]
leading underworld figures, ie notorious criminals 黑社会的头面人物（劣迹昭彰的罪犯）.