The surname Dalmasso and its derivatives sink their roots in medieval northern Italy, especially in Piedmont and, by extension, in the neighbouring regions of Liguria, Lombardy and the Veneto. Its genesis is associated with the Latin personal name Dalmatius ("the one who comes from Dalmatia"), and with vernacular forms such as Dalmazio or Dalmasio.

Etymology and historical forms

• Dal Mas / Dal Maso: A toponymic patronymic variant typical of the Treviso area, also very widespread in the areas of Belluno, Pordenone and the Veneto in general. In Vicenza, Verona or Padua it appears simply as Mas(o), a contraction of Tommaso.
• Dalmasso / Dalmaso: The most frequent form in Piedmont, with important nuclei in Cuneo and Turin. It is considered an evolution of Dalmatius (4th century), and could have been reinforced in the Late Middle Ages after the concession of privileges by the Pope Dalmazio de Bearn (14th century).
• Dalmasso and Dalmazzo are related both to the influence exercised on Ligurian-Piedmontese Christianity by the figure of Saint Dalmazzo and by the abbey erected in lower Piedmont and instituted in honour of that saint; it is not ruled out that it may also be a process of transformation into a surname of a place name derived from the area of Borgo San Dalmazzo, Cuneo.
• Dalmassi, Dalmasio, Dalmazzio, Dalmazzi, Dalmaccio, Dalmasse, Dalmazza, Dalmazze, Dalmazzon, Dalmazzini: Dialectal and Latinized variants, typical of Lombardy (Milan) and of the Trentino on the border with Vicenza.
• Dalmata, Dalmatico, Dalmatelli: Derivatives that allude explicitly to the region of Dalmatia as the geographical origin.