黑社會 angolul

triad [triads]▼(underground society)
noun
[UK: ˈtraɪæd] [US: ˈtraˌjæd]

underworld▼(part of society engaged in crime or vice)
noun
[UK: ˈʌn.də.wɜːld] [US: ˈʌn.dəˌr.wərld]