E. De Felice proposes a double origin for this surname: on the one hand, as an ethnic name derived from the place name Soddi, a locality in the province of Oristano, in Sardinia; on the other, as a nickname from the Sardinian word sòddu, meaning "wage, penny".

V. Blunda also records the surname as derived from the dialectal word sòddu, but from a Sicilian perspective: the word would designate a low-denomination coin, the smallest piece of the popular monetary system. According to Blunda, the surname may have originated in a nickname applied to someone connected with money-changing or petty trade in the marketplace.

Both authors agree on the dialectal etymon sòddu, though they place it in different regional contexts: De Felice within a Sardinian setting, and Blunda within a Sicilian one, with a more specific semantic nuance tied to the world of commerce.