The surname Prearo presents an uncertain origin, with different possible interpretations. In this sense, E. Rossoni proposes an anthroponymic origin, linking it with the Germanic name Priarius, documented in historical sources of Antiquity, which would indicate a continuity of ancient personal names in the formation of the surname.

For his part, F. De Laurentiis puts forward a nickname interpretation of a Venetan scope, derived from the term prearo, related to the idea of "prior" or "first," applied as a byname to distinguish the firstborn, one who stood out in competitions or one who performed the main functions at work. In this way, the surname may reflect both an origin in an old personal name and a descriptive designation arisen in local contexts.