The authors agree that the surname derives from a name of medieval Germanic origin. E. De Felice documents it in Italy from the 11th century in the Latinized forms Guiscardus, Guicciardus, Guizardus and Viscardus, with variants such as Guicciardo, Guizzardo and Viscardo. The Germanic name, a Visichard, is compounded from *wisa- (German weise: "wise, expert") and *hardhu- ("hard, strong, valiant"), and shows in Italy a multiple tradition: Franco-Norman and French chivalric.

Both authors note the historical weight of Robert Guiscard, Norman duke of Apulia, Calabria and Sicily from 1059, whose prestige contributed to the spread of the name. E. Rossoni specifies that the surname is very rare and links it especially to Naples, deriving it from the medieval Norman form Wiscard.

De Felice offers a more detailed geographical distribution: Guiscardi appears in central and southern Italy; Guicciardi, in Tuscany; Guichardy, in the Aosta Valley; Guizzardi, in Emilia-Romagna; and Viscardi, in Liguria and Naples, with Biscardi in the continental south.