The media uses it in headlines like they use the word Mob. Mafiosi never use the word, although Buscetta used it when he began to talk to the magistrates.
The old time mafiosi used the word La Cosa Nostra (The Thing of Our) or the organization,the family etc because before the corleonesi reign,only who was made can use the word La Cosa Nostra and who use the world gave to himself an importance that in the facts never had was easly whacked.Now is more common and the 2 words La Cosa Nostra and Mafia are used as synonyms.
