The authors differ on the origin of the surname. F. Miranda proposes several etymological hypotheses. The first derives it, together with its variants Sozio and Suzzi, from the aphaeresis of the place name Besozzo, a comune in the province of Varese. The second links it to Greek sòzzu, with the sense of "solid, massive", or to sokòs, "active, strong". The third relates it to the dialectalisation of Latin socius, "associate, friend, companion", which in old Italian had become sozio. Miranda also mentions the form Sòczu as a possible starting point, without specifying its origin.

V. Blunda, by contrast, confines the surname to the Sicilian sphere and considers it of dialectal origin. He derives it from the word sòczu, meaning "fat, obese", an adjective of popular Sicilian speech that describes a bulky build. According to Blunda, the surname would have arisen as a physical nickname applied to a person of notable stoutness within their community.

It should be noted that the form sòczu appears in both authors, but with different senses: Miranda associates it with "active, strong", while Blunda attributes to it the meaning "fat, obese". Both readings are possible within the Sicilian dialectal lexicon, though they are semantically opposed. Miranda notes that the surname is present in several regions of Italy, among them Lombardy, Emilia-Romagna, Tuscany, Liguria, Lazio, Sicily, Piedmont and Apulia, with a notable concentration in the Catania area and in other Sicilian provinces such as Ragusa, Palermo, Syracuse, Agrigento and Enna.