Scholars agree that this surname derives from the Italian term incognito, meaning "unknown," and was assigned to orphans and foundlings whose father's identity was not known. It belongs to a well-documented category of surnames created specifically to identify children of unknown parentage, alongside names such as Trovato, Esposito, Innocenti, Di Dio, D'Ignoto, Diolosà, and Diotallevi. It is recorded in Italy as a surname of orphans.

F. Miranda locates the principal area of origin in Sicily, where the surname is documented in the provinces of Catania, Messina, Palermo, Syracuse, and Enna. From Sicily it spread, with a more limited presence, to Lombardy, Piedmont, Calabria, Campania, Lazio, Emilia-Romagna, and Veneto. G. P. Holmes agrees on the meaning and on the connection with surnames of the same type, though he adds no further geographical detail.