The authors agree that this surname has its origin in place names of southern Italy, in particular in Geraci Siculo, in the province of Palermo, and in Gerace, in the province of Reggio Calabria, from which the parallel form Gerace comes.

F. De Laurentiis specifies that the surname is diffused in Calabria and in Sicily: in Calabria it refers to the place names Gerace and, in part, to Gerace Marina, which was the official name of Locri until 1934; in Sicily, especially in the western part, the reference is Geraci Siculo, in the province of Palermo. In both cases, the local demonyms would also have contributed to the formation of the surname.

G. Rohlfs notes that the surname is of Greek-Byzantine origin and constitutes a form kindred with Gerace. He connects it with the Greek term ἱεράκι, meaning "sparrowhawk", and observes that in Greece the form Gerakis survives as a surname. Rohlfs documents it throughout Calabria and also as a Sicilian surname.

F. Miranda develops the etymology in greater detail and distinguishes three hypotheses: that it derives from the Greek surname Gerakis, in turn from the Greek term ieràki ("sparrowhawk", according to Rohlfs); that it comes from the Greek jerakiòn ("falcon" or "little falcon", according to Pensabene and Caracausi); or that it originates in the Byzantine Hagia Kuriaké ("Saint Kyriake", according to De Felice). Miranda also considers possible the derivation from the place names Geraci Siculo, Gerace and Gerace Marina (today Locri), in Calabria.

E. Rossoni limits himself to noting the derivation from the place name Geraci Siculo, in the province of Palermo, and refers to the entry Gerace for complementary information.

Geographically, Miranda indicates that the surname is present in Sicily predominantly, with zones of concentration in the provinces of Palermo, Messina, Catania, Agrigento, Caltanissetta and in the Enna area. It also appears, with a lesser presence, in other regions: Lombardy, Piedmont, Lazio, Tuscany, Liguria, Calabria, Veneto, Emilia-Romagna and Campania.