The authors agree that this surname derives from the Greek kalóghēros, composed of kalós ("beautiful" or "good") and ghéras ("old age"), with the original sense of "good old man" or "monk". The Modern Greek form designated the monks of the Byzantine rite and, by extension, came to be used as a term of religious reverence.

E. De Felice specifies that, in the Griko-speaking zones of the extreme south of Italy, the surname does not come mainly from the cult of Saint Calogero —hermit and martyr of Constantinople of the 5th century— but from the Modern Greek appellative kalógheros applied to the monks. He also notes that from the sense "monk" derived figuratively the popular name of the blue tit. A. Bongioanni links the surname with the cult of Saint Calogero (5th century, feast on 18 June) and mentions an old church in Milan dedicated to this saint.

G. Rohlfs highlights its presence throughout Calabria, in the Naples area and in Sicily, emphasising its Greek-Byzantine root and noting that the term survives as a surname in Greece. V. Blunda places it especially in Sicily, where it entered by Christian route in honour of the saint. Bongioanni mentions related forms in Piedmont, such as Calosso —a surname and place name in the Asti area— and possible Lombard-Piedmontese variants such as Lossa and Losio.