G. Rohlfs proposes a Greek-Byzantine origin for this surname, documented in the province of Catanzaro —in the region of Calabria— and coinciding with the name of the contrada Ròdano of Dàvoli. He derives it from the Greek ῥόδινος, with the meaning of "red, rosy," linking it to the same lexical family as the surname Rodinò. Rohlfs frames it as a reflection of the Byzantine presence in southern Italy.

R. Brondolo, on the other hand, records for the Acquese area —in southern Piedmont— a dialect form Rudàn- and proposes a completely different etymology. According to this author, the surname could go back to rodaria, a term that designated a medieval tributary district linked to the alpine routes. From rodaria would have derived rodario and, possibly, rodariano, a form from which, by syncope, the present-day surname could come.

Both proposals are independent of each other and reflect different geographic and etymological origins: a Greek root in Calabria and a medieval Latin root in southern Piedmont, which suggests that the surname presents independent lines of origin arisen in different regions without a direct relation between them.