Americans shortened the word delicatessen to deli in the mid-1900s. At the same time, more people began to frequent these stores as the menus expanded beyond the owner's ethnic roots. For example, pastrami had become a popular item in delis, but only the Americanized version of it.

A delicatessen, or in short, a “deli,” is a store where people can go to buy ready-to-eat items such as cold cut meats, sliced cheeses, sandwiches, breads, salads and so much more. If you're from the Mid-Atlantic or New England areas, you probably have a favorite deli — or a list of at least a few favorites!

The word deli is a shortened form, or common nickname, of delicatessen, an American English version of the German delikatessen, the plural of delikatesse, "delicacy," or "fine food." Many delis specialize in the food of a certain region, country, or ethnicity — like a Jewish deli, a German deli, or a Greek deli.

In the US, a deli is a store selling cold cuts, cheeses, and a variety of salads, as well as a selection of unusual or foreign prepared foods. I imagine, if you are looking at a menu, and something is served deli style in the US, it probably means that it is the kind of sandwich you'd find in a deli.