Source : Webster's Revised Unabridged Dictionary (1913)

Maffioso \Maf`fi*o"so\, Mafioso \Ma`fi*o"so\, n.; pl. {-si}.
   [It. maffioso.]
   A member of the maffia.

Source : WordNet®

mafioso
     n 1: a member of the Sicilian Mafia
     2: a member of the Mafia crime syndicate in the United States
     [also: {mafiosi} (pl)]