Final answer:
The term 'sub' refers to a sandwich known by various regional names such as 'hoagie' in Philadelphia, as well as 'hero', 'grinder', and 'po' boy' in other areas.
Step-by-step explanation:
The term "sub" is commonly used to refer to a large sandwich made with a long roll and filled with meats, cheeses, vegetables, and condiments. This type of sandwich is known by various names throughout the United States and beyond.
In Philadelphia, the term used is "hoagie," which refers to the same type of sandwich as a sub. Other words used for these sandwiches include hero, grinder, and po' boy, and these terms can vary based on regional dialects and local food culture.