The authors agree that the surname derives from the medieval name Selvaggio (feminine Selvaggia), formed from the adjective selvaggio —in old forms, salvaggio—, which in the Middle Ages and the Renaissance designated one who lived and worked in the woods or far from inhabited centres. By figurative and pejorative extension, it was also applied to one who was rough, harsh, fierce or inhuman.

E. Rossoni documents the transformation into a surname from the 13th century, when Matteo Selvaggio appears recorded as a feudatory of Frederick II of Swabia in the territory of Scaletta. Rossoni notes that Selvaggi is typical of the Bari, Matera and Cosenza areas, while the variant Selvaggio has its main presence in Sicily.

E. De Felice does not add specific geographic details, but highlights the sporadic character of the surname in Italy and underlines the semantic journey of the base term, from its original descriptive use to its pejorative connotations in medieval and Renaissance language.