The authors agree that the surname derives from a place name: for the Sicilian line, from the city of Ragusa —today the capital of the homonymous province—; for the Adriatic-coast line, from the Dalmatian Ragusa, present-day Dubrovnik, linked to Dalmatian merchants settled in Apulia.

F. Miranda develops the etymology of the place name: in the Byzantine period the forms Ragous and Rogos are documented, with the meaning of "granary," alluding to the fertility of the territory. With the Arab domination it derived into Ragus or Rakkusa ("famous place"); in the Norman and Aragonese period it appears as Rausia, and only in the 18th century was the form Ragusa fixed. Some researchers postulate an evolutionary chain that would start from the Greek Heraea, passing through Heresium, Resium, Reusia, Rakkusa and Ragusia, until reaching Ragusa.

E. Rossoni notes that the surname is documented in a deed of Solofra of 1521. As to the distribution, Ragusa is proper to Sicily; Raguseo is typical of Molfetta, in the Bari area; Raguso is diffused in Gravina di Puglia and Martina Franca, in the Taranto area; Ragusin seems of Trieste origin; Ragusini is even rarer. Miranda specifies that in Sicily the surname is present in all the provinces, with a greater concentration in the Catania, Ragusa and Palermo areas, and also notes nuclei in Lombardy, Piedmont, Lazio, Apulia, Liguria, Veneto, Tuscany, Calabria, Campania and Emilia-Romagna.