E. Rossoni considers this a typically Sicilian surname, derived from a nickname or from a modification of the Latin cognomen Delicatus.

F. Miranda develops this hypothesis in greater detail: the surname would come from a nickname given to the first bearer (non delicato, "not delicate"), or from a modification of the Latin cognomen Delicatus with an intensifying prosthetic in-. Miranda adds a third possibility, taken from the linguist Rohlfs: the form In-Delicatus would originally have designated the woman married to a Delicato.

Although its area of origin is Sicily —where it is documented in every province, with the greatest presence in the Catania, Agrigento, Trapani, Palermo and Messina areas—, Miranda notes that the surname is also found in Apulia, Emilia-Romagna, Friuli-Venezia Giulia, Lazio, Liguria, Lombardy, Piedmont, Tuscany and Veneto, these last being regions with strong southern immigration.