The authors agree that this surname is of dialectal origin, derived from the Sicilian word cùgnu. F. Miranda notes that the term designates an instrument of metal or wood with the shape of a triangular prism and a very acute angle, used to split or separate bodies, and that the surname was probably linked to the trade of the first bearer or to a trait of character, since cugnu is used in a figurative sense to describe a person of firm or determined character.

V. Blunda broadens the analysis by noting that cùgnu is a polyvalent term that also means "hill" or "mound", by the analogy between the triangular shape of the wedge and that of an isolated elevation in the Sicilian landscape. According to Blunda, the surname could have originated in a minor place name referring to a house situated beside an orographic cugnu, or in a nickname applied to a person of compact and robust build.

Miranda documents its presence in Sicily —especially in the Syracuse, Ragusa, Catania, Enna and Agrigento areas— and in Piedmont, with lesser diffusion in other regions such as Lombardy, Lazio, Liguria, Veneto and Basilicata.