It's an Italian surname. It is an Italian brand of very fine felt hats. There is also a hat with that same name, of the same brand. Name of a 1970 film, with Jean-Paul Belmondo and Alain Delon.
BORSALINO 1 . Company and business of Alessandria, Italy of renown that invented the short wing hat 2 . Fedora hat, invented by the company Borsalino, and which is also called by that name.