Bologna sausage is an American version of the Italian mortadella (a finely hashed/ground pork sausage with lard pieces). Only the American version can be made out of chicken, turkey, beef or pork. It is commonly called bologna and often pronounced and/or spelled baloney (or boloney).

This food is usually served in round uniform slices pre-cut in a package or sliced by the butcher. It is popularly produced and sold by Oscar Mayer, which had a famous ad campaign in the 1970s with a well-known jingle ("My bologna has a first name, it's O-S-C-A-R..."). There are many other manufacturers as well, including local butcher shops and grocery meat counters.

Bologna sausage is typically served in a sandwich, often for lunch; hence, it is perhaps the most common "lunch meat" in the US. However, bologna may also be served fried or wrapped around mashed potatoes and baked as a version of "pigs in a blanket".

Bologna sausage is commonly believed to be created from lowly scraps of meat cuts. It is assumed that this food, therefore, is the origin of the slang word baloney, which means nonsense (similar to "hogwash") and is often used as an expletive.