The authors agree that the surname has a notable presence in Sicily, although its distribution reaches also other regions of northern and central Italy, such as Piedmont, Lombardy, Liguria, Emilia-Romagna, Veneto, Lazio, Calabria and Abruzzo.

F. Miranda proposes three etymological hypotheses. The first derives it from an aphetic form of the medieval name Amolinus. The second links it to the Greek μυλών ("mill"), from which the forms molinè, mulonè and molonia would come. The third suggests that it could be the Italianization of the Sicilian dialect term muluni, with the meaning "watermelon".

V. Blunda inclines exclusively towards this last etymology and develops the nickname hypothesis: the term mulùni would have given rise to the surname either as a nickname applied to a stout, round-headed person, or as a designation of the grower specialized in that vegetable, whose cultivation flourished in the irrigated gardens of the Sicilian interior.