This is the 4583rd most frequent Polish word.
mafii
The Polish word "mafii" means "mafia" (genitive singular or dative singular/plural form of "mafia").
The term "mafii" is used to refer to an organized crime group in the genitive case following grammatical rules in Polish.
On powiedział, że należy do mafii.
He said that he belongs to the mafia.
Here, "mafii" is in the genitive case as it specifies possession or origin, relating to "Italian mafia."
Książka opisuje historię włoskiej mafii.
The book describes the history of the Italian mafia.
In this sentence, "mafii" is in the genitive case, governed by the preposition "przeciwko" (against).