The authors differ on the origin of this surname, pointing to two distinct and geographically separate etymologies.

E. De Felice links it to the place names Gèssi and Gèsso, two small localities in the municipality of Zola Predosa, in the Bologna area. F. De Laurentiis agrees with this reading and notes that the surname is found precisely in that Bolognese area, derived from those place names and their demonyms.

V. Blunda proposes, by contrast, an entirely independent Sicilian origin: the surname would come from the dialect word ggèssa, which in Sicilian means "holm oak, oak". Blunda warns that the popular reading associating it with Italian gesso ("plaster") is a false etymology, and places it within the family of Sicilian surnames derived from the Latin etymon quercus, alongside Cerci, Cessa and Cesso. Its fixing as a surname may be due to a microtoponym designating the place where someone lived near a well-known oak, or in a spot with an abundance of these trees, characteristic elements of the Sicilian rural landscape.

The surname therefore has independent origins in different regions of Italy: one with a toponymic base in Emilia-Romagna and another with a phytotoponymic base in Sicily.