The authors agree that this is a surname typical of Piedmont, with a presence concentrated in the Cuneo, Asti and Turin areas. E. Rossoni notes that the most representative areas include localities such as Verzuolo, Savigliano and Saluzzo in the Cuneo area, as well as Asti and Montafia in the Asti area. F. Miranda adds that, outside Piedmont, there are smaller presences in Liguria, Lombardy, Lazio and Tuscany, and that in Sicily the surname appears specifically in the Enna area, in the locality of Centuripe.

As to the origin, the authors agree in proposing three hypotheses. The first is a derivation from the late-medieval name Rubasius —Rossoni dates it in a chronicle of 1582, while Miranda records it as Rubasio. The second points back to the place name Roasio, a municipality in the province of Vercelli, or to Bricco Roasio, a frazione of the municipality of Asti. The third hypothesis, considered alternative, links the surname with the Piedmontese term ruai, which designates a thicket or wasteland, applied to cold and windy terrain, therefore uncultivated. Rossoni considers this last the most probable derivation.

The surname Rovasio, mentioned by Rossoni, is much rarer and also of Piedmontese origin.