The authors agree that this surname derives from the late Latin cognomen Gerardus or from the medieval name of Germanic origin Gerhard. F. Miranda specifies that this Germanic name is composed of the terms ger (or gaira, "spear") and hart (or hard, hardu, "hard, strong"), with the sense of "strong with the spear" or "strong warrior". E. Rossoni adds that in southern Italy it is more probable that the surname comes from the Norman name Geraldus.

The surname presents multiple independent stems of origin (ceppi), arisen in different regions without a direct relation between them. The authors agree in pointing to specific zones in Veneto, Lazio, the province of Potenza and the Salento area —that is, the southernmost zone of the Apulia region, in southern Italy—, with a presence also in Sicily, particularly in the Trapani area. Miranda adds that in Sicily the surname also extends through the Palermo, Agrigento, Catania and Messina areas, and that its diffusion reaches regions such as Basilicata, Apulia, Piedmont, Lombardy, Friuli-Venezia Giulia, Tuscany and Campania.