maffia(n = noun.group) cosa nostra, mafia - a crime syndicate in the United States; organized in families; believed to have important relations to the Sicilian Mafia;
maffia(n = noun.group) mafia, sicilian mafia - a secret terrorist group in Sicily; originally opposed tyranny but evolved into a criminal organization in the middle of the 19th century;
A secret society which organized in Sicily as a political organization, but is now widespread among Italians, and is used to further or protect private interests, reputedly by illegal methods; called also the Sicilian Mafia. [Webster 1913 Suppl.]
A group of loosely associated of criminal organizations in the United States, some having ties to the Sicilian Mafia, and organized in “families”; the term is applied to the entire group of organizations, or to any one local group. Also, loosely, organized groups of criminals anywhere, as the Russian mafia. [WordNet 1.6]
Any tightly knit group of trusted associates having strong control or influence in some area; as, Kennedy and his Irish Mafia. [PJC]