The Collaborative International Dictionary of English v.0.48:

Maffioso \Maf`fi*o"so\, Mafioso \Ma`fi*o"so\, n.; pl. -si.
   [It. maffioso.]
   A member of the mafia.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Mafia \Maf"i*a\, Mafioso \Ma`fi*o"so\, n.
   see maffia, maffioso.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

mafioso
    n 1: a member of the Sicilian Mafia
    2: a member of the Mafia crime syndicate in the United States

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "Mafioso":
   Young Turk, beast, beldam, berserk, berserker, black marketeer,
   bomber, bootlegger, brute, dealer, demon, devil, dragon,
   drug pusher, fiend, fire-eater, firebrand, fury, goon, gorilla,
   gray marketeer, gunsel, hardnose, hell-raiser, hellcat, hellhound,
   hellion, holy terror, hood, hoodlum, hothead, hotspur, incendiary,
   killer, mad dog, madcap, monster, moonshiner, mugger, pusher,
   racketeer, rapist, revolutionary, savage, she-wolf, spitfire,
   termagant, terror, terrorist, tiger, tigress, tough, tough guy,
   ugly customer, violent, virago, vixen, wild beast, witch, wolf