2. 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 Noun
3. An explosive device that is set off in an oil well (or a gas well) to start or to increase the flow of oil (or gas) Noun
4. A small firework that consists of a percussion cap and some gravel wrapped in paper; explodes when thrown forcefully against a hard surface Noun
5. A small explosive device that is placed on a railroad track and fires when a train runs over it; the sound of the explosion warns the engineer of danger ahead Noun
6. Armament consisting of a long cylindrical self-propelled underwater projectile that detonates on contact with a target Noun
7. Any sluggish bottom-dwelling ray of the order Torpediniformes having a rounded body and electric organs on each side of the head capable of emitting strong electric discharges Noun