social group - people sharing some social relation

yakuza - organized crime in Japan; an alliance of criminal organizations and illegal enterprises

gang, mob, pack, ring - an association of criminals; "police tried to break up the gang"; "a pack of thieves"

underworld - the criminal class

Sicilian Mafia, Maffia, Mafia - a secret terrorist group in Sicily; originally opposed tyranny but evolved into a criminal organization in the middle of the 19th century

Black Hand - a secret terrorist society in the United States early in the 20th century

Camorra - a secret society in Naples notorious for violence and blackmail

crime syndicate, syndicate, mob, family - a loose affiliation of gangsters in charge of organized criminal activities