F. De Laurentiis and E. Rossoni agree that the surname is proper to northern Italy and may derive from various place names or from a dialect nickname.

De Laurentiis notes that it reflects various place names of the Ranzo type (in the provinces of Trento and Imperia), Ranzano (in the provinces of Pordenone and Parma) and Ranzi (in the province of Savona). He adds that it could also derive from the nickname formed from the Venetan-Emilian dialect term ranzo ("rancid"), referring to a person who is old, antiquated, out of fashion, of stale ideas.

Rossoni agrees on those hypotheses and adds others: a possible derivation from place names such as Ranzanico (Bergamo area) or Baranzate (Milan area), or else from the dialect term ranza ("a Bergamasque-type sickle"), which would indicate the agricultural activity of the family.