The authors agree that the surname was formed from the name Ambrogio, derived from the Greek Ambròsios ("immortal"), consolidated by the cult of Saint Ambrose of Milan.

A. Bongioanni identifies it as a Greek given name, derived from ambrosius. He recalls that Sant'Ambrogio was bishop of Milan in the 4th century, celebrated on 4 April and 7 December. He notes that, through the darkening of the vowels o and u in the Venetian and Friulian dialects, the forms Brugi, Brusato, Brusin and similar ones arise. He considers that it is not ruled out, since the alternation between o and a is frequent, that Brasini and Brasioli also come from here.

V. Blunda, for the Sicilian variant, derives it from the Greek etymon Ambròsios. He notes that the root goes back to ambrosia, the food of the Olympian gods according to Greek mythology. He adds that the name was Christianised by the cult of Saint Ambrose of Milan (4th century), one of the great figures of Western patristics, and reached Sicily both through the Byzantine liturgy and through the later Latin influence.