E. Rossoni notes that this surname may derive from a dialect deformation of the Greco-Latin name Kyriakus. In its Sicilian variant, he also points to the possibility that it comes from dialect modifications of the place name Geraci Siculo (in the province of Palermo), of Geraci (in the province of Enna) or of Gerace (in the province of Reggio Calabria). Geographically, Rossoni indicates that Irace is typical of the Naples area, while Iraci is clearly Sicilian, with its greatest concentration in Palermo.

G. Rohlfs offers a different etymology: he considers the surname of Greco-Byzantine origin and places it in the family of Gerace/Jeraci, derived from the Greek ἱεράκι, meaning "sparrowhawk". Rohlfs documents its presence in Reggio Calabria, alongside the Neapolitan and Sicilian forms Iraci, and refers the reader to the entry Jeraci for fuller treatment.

Both authors agree in recognizing the variants Irace and Iraci and in associating them with southern Italy —Campania, Sicily and Calabria—, but they differ on the etymology: Rossoni proposes a derivation from the personal name Kyriakus, while Rohlfs links it directly to the toponymic surname Gerace/Jeraci and to the Greek root ἱεράκι ("sparrowhawk").