Literally "Our case" or "Our business", Italian term. Especially used a lot in reference to the mafia. Also a synonym for mafia. Both sort of forbidden words, not used in Godfather 1.
The Cosa Nostra are fighting the Colombians.
Used by Sicilian gangs, it is now a separate branch of organized crime. It's meaning is literally, "This thing of ours". It goes back hundreds of years, when the Mafia was invented to protect Sicilian families from maurauding gangs and conquerers.
Lucy Luciano was known for bringing La Cosa Nostra to the United States.
"Our Thing" or "This Thing Of Ours". The real name for the Mafia. Cosa Nostra is a crime sydicate that began in Sicily
in the mid nineteenth century. A "Made Man" is a man that has become a member of Cosa Nostra. According to original Cosa Nostra rules, you had to be of Sicilian descent to be a member, you couldn't have a close relative that was a police officer, etc. Many political leaders have been murdered by Cosa Nostra.
Kiss the Don's ring or die. This is Cosa Nostra.