The authors agree that this is a Sicilian surname of dialect origin, derived from the Sicilian term gèrfu. E. Rossoni locates it specifically in Misilmeri and in Palermo, and notes that the word refers to something sour or harsh, suggesting an origin in a nickname.

V. Blunda broadens the meaning of gèrfu as "harsh, bitter, uncultivated" and proposes that the surname may have arisen from a nickname applied to a person of gruff manner, or else from a microtoponym linked to land of poor quality. Blunda further records the variant Gelfo as an independent surname with the same etymon.