Meaning

noun any tightly knit group of trusted associates

noun a crime syndicate in the United States; organized in families; believed to have important relations to the Sicilian Mafia

noun a secret terrorist group in Sicily; originally opposed tyranny but evolved into a criminal organization in the middle of the 19th century

originBorrowed from Italian mafia, of uncertain origin. In the first instance, it is not clear whether the lemma in question is a Sicilian exonym or endonym, since written and oral sources on this term are scarce, the etymology remains uncertain and it's worthy of further investigation. It is possibly a regional term of the then recently established Kingdom of Italy; thus the meaning "spirit of…

Etymology from Wiktionary, CC BY-SA 3.0