The noun torpedo is a common noun, a word for any torpedo of any kind.
A proper noun is the name of a specific person, place, thing, or a title; for example:
- Torpedo, PA 16340
- Torpedo Road, Stafford Township, NJ
- Sierra Nevada Torpedo (beverage), Sierra Nevada Brewing Co.
- "Torpedo Run", 1958 movie with Glenn Ford and Ernest Borgnine
- "Torpedo", a novel by Ray Verola