The modern torpedo is a self-propelled weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with its target or in proximity to it.

The word torpedo comes from the name of a genus of electric rays in the order Torpediniformes, which in turn comes from the Latin 'torpere' (to be stiff or numb). In naval usage, the American Robert Fulton introduced the name to refer to a towed gunpowder charge used by his French submarine Nautilus (first tested in 1800) to demonstrate that it could sink warships.

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