F. Miranda notes that this surname derives from a nickname linked to the mountainous provenance of the first bearer, or else from place names containing the root mont-, abundant in Italy, all coming from the Latin mons-montis. It is an infrequent surname, concentrated mainly in Sicily, with a presence in the provinces of Catania, Messina, Palermo, Enna and Syracuse; in the Enna area it is documented in the municipalities of Regalbuto and Centuripe. It also appears in specific areas of Lombardy, Emilia-Romagna, Sardinia, Lazio, Veneto and Piedmont.

Miranda also records the compound surname Montagno Castagnolo, typical of the Messina area, present as well in the province of Catania (Bronte and Maniace) and in that of Enna (Regalbuto). The second component, Castagnolo, would derive from nicknames based on the term castagnola ("little chestnut") or from localities of the same name.

G. P. Holmes agrees on the Latin etymology of the term "mountain" and adds that the surname would have its origin at Tortorici, a locality in the province of Messina, in Sicily.