Noun
(New York City, food) A loaf bread which contains chunks of prosciutto and provolone, using lard.
(by extension) Similar loaf breads which contains other sorts of deli meats, other cheeses, and using other oils and fats.
(by extension) A loaf bread filled with leftover bits of meat and cheese, and other remains.
Used other than figuratively or idiomatically: see prosciutto, bread. (ie. bread with prosciutto slices on top)
Source: en.wiktionary.org