The authors differ significantly on the origin of this surname. E. Rossoni links it to the place name Casoria, a locality of the Naples area. He proposes two complementary readings: on the one hand, a possible relation of dependence or devotion towards the bishop of Naples, who in the late medieval period resided in that city; on the other, a derivation from the Latin casa aurea ("golden house"), alluding to the characteristics of the place of residence. Rossoni places the surname in localities such as Cicciano and Acerra, both in the region of Campania.

V. Blunda, on the other hand, proposes an etymology of Greek origin: it derives from casòrion, a Greek word that designated a brothel. According to this interpretation, the surname would have arisen as a nickname applied to the one who ran or frequented that type of establishment. Blunda documents this form in Sicily, which suggests an origin independent of that noted by Rossoni and points to the possibility that the surname presents independent clusters of origin in different regions of Italy.