The authors agree that the surname Leopoldo derives from a given name of Germanic origin compounded from two elements: one related to "people" or "folk", and another meaning "bold" or "brave". A. Bongioanni identifies the second element as bald, pald or pold ("bold, brave"), and notes German variants in which the first element may be leut or liut ("people, folk"), giving rise to forms such as Luitpoldo, Luiboldo or Liubaldo. V. Blunda specifies the etyma as leudi ("folk, people, free men") and baltha ("bold, daring"), with the overall sense of "bold among the free men" or "valiant of the royal retinue".

Both authors mention Saint Leopold III of Austria as the reference figure for the name. Bongioanni calls him duke of Austria and sets his feast day on 15 November. Blunda specifies that he was margrave of the Eastern March and that he was canonized in 1485, becoming the Austrian national patron for his monastic foundations and his rule during the tensions between the Holy Roman Empire and the papacy.

Bongioanni notes that the surnames derived from this name are Leopardi —documented as Leopardus in the year 747—, Poldi and Polti. He also mentions the variant Leopardo, linked to a noble family of Friuli-Venezia Giulia. He warns that the surname Pardo must be excluded from this family, since it corresponds to an onomastic tradition of Spanish Jews.