E. De Felice links this surname to a nickname derived from Greek and from the Modern Greek of Albanian transmission, specifically from the term (i)schyrós, with the meaning of "strong." He places it in eastern Sicily, with a notable presence in Piana degli Albanesi.

G. Rohlfs agrees in noting a Greek origin, although he refers specifically to the classical form σκληρός, with the meaning of "hard." He documents it in the province of Reggio Calabria and also in Sicily, and notes that in Greece it survives as a surname under the form Skliròs.

E. Rossoni offers a different perspective: he considers that the surname is typically Venetan, with a presence in the Vicenza and Padua areas, besides some presence in the Palermo area. He proposes that it could derive from a dialect nickname based on the archaic Venetian term schiro, which designated a type of net used to catch birds. This etymology is independent of the Greek one and points to a northern origin.

The set of the sources suggests that the surname presents independent lines of origin (ceppi): one in southern Italy, of Greek or Greek-Byzantine root, associated with the communities of Albanian and Greek tradition of Sicily and Calabria, and another in the north-east of Italy, of probable Venetan dialect base, with a different semantic motivation.