The authors agree that this surname derives from a nickname referring to the reddish colour of the hair, beard or complexion of the first bearers, and that it goes back to the Late Latin adjective russus, used in place of rubeus.

F. Miranda notes that already among the Romans this characteristic had given rise to the surname Rossius, and that the presence of red hair was consistent both in the pre-Roman Celtic populations and among the Latins. He mentions as an example Lucius Cornelius Sulla, known for that physical trait, who lived between 138 and 68 BC. Miranda also indicates that the surname is linked with variants such as Rossi, Rossini, Rossetti and other derived forms.

E. Giraudo specifies that this surname belongs to the most characteristic surname type of Italy, represented by Rossi, and places its greatest concentration in the Cuneo area, with a notable presence in localities such as Busca, Savigliano, Sommariva Perno and Villanova Solaro.

As to the geographic distribution, Miranda notes that the surname extends across nearly a thousand municipalities of all the Italian regions, with a greater presence in Piedmont, Veneto and Liguria. It also appears in Friuli-Venezia Giulia, Lombardy, Sicily, Tuscany, Sardinia, Lazio, Campania, Trentino-Alto Adige, Emilia-Romagna and Calabria.