bun or pastry
Made in the form of a rosette, or a spiral, and often used for sandwiches. There are many different recipes; a rosetta romana or rosetta soffiate is light and airy, made with brewers' yeast.
The word can mean other things: various cookies and pastries, or the design a good barman can paint with milk on top of a cappucino. Rosette emiliane are a sheet of dough covered with a layer of ham and cheese, rolled up and cut into slices and baked, maybe with tomato or bechamel on top of the slices.