From  sanna or zanna meaning "tusk, fang", a nickname for a person with a protruding tooth.

The authors agree that it is a surname characteristic of Sardinia, derived from a nickname based on the Sardinian dialect term sanna, which means "fang" or "large, prominent tooth." The denomination would be applied to people with very developed front teeth.

E. De Felice notes that the term also functioned as a name and nickname, both feminine and masculine, and that it is documented from the Condaghi —medieval Sardinian cartularies— with a presence especially marked in the Cagliari area, the Campidano and the Sassari area.

E. Rossoni broadens the etymology and traces the term back to the Old Italian sanna, and further back to the Lombard zan and the Germanic zahn. He further adds that the word could also designate a rocky outcrop, so that the nickname could equally be applied to those who lived near a formation of that type. Rossoni documents the surname in the Peace of Eleonora of 1388, where twenty-seven people bearing it appear, and observes that its greater concentration in the centre-north of the island suggests a Logudorese or Gallurese origin.