Source : Webster's Revised Unabridged Dictionary (1913)

Maffia \Maf"fi*a\, Mafia \Ma"fi*a\, n. [It. maffia.]
   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.

Source : WordNet®

Mafia
     n 1: a crime syndicate in the United States; organized in
          families; believed to have important relations to the
          Sicilian Mafia [syn: {Maffia}, {Cosa Nostra}]
     2: a secret terrorist group in Sicily; originally opposed
        tyranny but evolved into a criminal organization in the
        middle of the 19th century [syn: {Maffia}, {Sicilian Mafia}]
     3: any tightly knit group of trusted associates [syn: {maffia}]