submarine sandwich

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Also called regionally A large sandwich consisting of a long roll split lengthwise and filled with layers of meat, cheese, tomatoes, lettuce, and condiments.

from the GNU version of the Collaborative International Dictionary of English.

• noun A large sandwich on an elongated roll, usually incompletely cut into two halves, filed with various cold cuts, meatballs, lettuce, cheese, tomatoes, olives, etc., and spiced variously, and often having oil or other dressing applied; called also hoagie, hero, hero sandwich, grinder, sub, submarine, poor boy, and Italian sandwich. A single such sandwich may consitute a substantial meal. Very large variants are sometimes prepared for social gatherings and cut into pieces for individual consumption.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a sandwich made on a long roll split lengthwise

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States