E. Rossoni proposes that the surname would derive from the Latin term propago, which designates the cutting, the shoot of a plant or, more specifically, the vine shoot. He notes that it would be one of the first noble families of Piedmont, with very ancient origins, and locates its present-day presence in the Crema area, in the province of Cremona.

F. Miranda agrees on the Latin etymology, describing propago as a term referring to propagules, plant branches or vine shoots. Miranda specifies the geographic distribution: the surname is diffused in around thirty-five municipalities, mostly Lombard, with specific areas also in Piedmont, Liguria, Veneto and Sicily —particularly in the Enna area, in the municipality of Regalbuto.