A crime family is a term used to describe a unit of an organized crime syndicate, often operating within a specific geographic territory. The term is used almost exclusively to refer to units of the Mafia, both in Sicily and in the United States, although it is occasionally used to refer to other groups.
The origins of the term come from the Sicilian Mafia. In the Sicilian dialect, the word cosca, which literally translates into artichoke (a multi-layered vegetable surrounding a vital core), is also used for clan. In the early days of the Mafia, loose groups of bandits organized themselves into associations that over time became more organized, and they adopted the term based on both of its meanings.
The term can be a point of confusion, especially in popular culture and Hollywood, because in the truest sense, crime families are not necessarily blood families who happen to be involved in criminal activity, and not necessarily based on blood relationships.
It can further be speculated that the Mafia was simply emulating, to a certain degree, a more medieval order in which a noble family would more or less serve as the power in a local village, in a sort of inverted hacienda culture.
Nevertheless, the term stuck, both in the minds of popular culture as well as the national law enforcement community, and eventually began to be used to describe individual units of not Sicilian and Italian gangsters.