From Wikipedia

Crime Inc. - The True Story of the Mafia
Episode One

All in the Family

The American Mafia (or simply the Mafia in the United States), also known as Cosa Nostra or La Cosa Nostra, is an Italian-American criminal society and offshoot of the Sicilian Mafia. Much like the Sicilian Mafia, the American Mafia had no formal name and is a secret criminal society. Its members usually refer to it as Cosa Nostra or by its English translation "our thing". Another translation/meaning of the term is "this thing of ours". The press has also coined the name "National Crime Syndicate" to refer to the entirety of U.S. organized crime, including the Mafia.