That was how a student described torpedo. The word has certainly gone through an unexpected progression of meanings.  In English, for instance, when the original audience of Christopher Marlowe’s Edward II heard Piers Gaveston, the King’s favourite, described as ‘that vile torpedo’, the image conveyed at that time was of a flat round, brown fish lying on the seabed waiting to numb its prey electrically.  Four centuries later, the hearers’ first image would be of a huge long cigar-shaped missile speeding through the water to destroy a ship.

A timeline of its meanings:

LATIN:  torpēdo, ĭnis, f.

1.  stiffness, numbness, inflexibility, sluggishness, torpidity: physical or mental.

tanta torpedo invaserat animum ut, si principem eum fuisse ceteri non meminissent, ipse oblivisceretur
—Tacitus, Histories III.63 (on the emperor Vitellius)
¶  Such a numbness had infected his spirit, that if the others had not remembered he had been emperor, he would have forgotten it himself.

2.  by metaphora, the cramp-fish, able to stun its victims, and fishermen: mentioned, for instance, by Cicero in De Natura Deorum, where he lists the means by which various animals are able to defend themselves.

ENGLISH:  torpedo         

3.  (1527) a flat fish, also known as the cramp-fish, almost circular in shape, like a fat pancake with a tail, which lies on the seabed and catches its prey by numbing them—since its body is equipped with a pair of cunningly designed electric batteries. This meaning is still in use by marine biologists to denote one of the genera of electric fish, which include sting-rays.

4.  (1593) By metaphora, any person with the power of numbing someone else’s faculties, feelings or moral sense. Hence the description of Piers Gaveston mentioned above. 

5.  (1776) an aquatic mine, left to explode under an enemy ship after a timed interval. These seem to have been first devised in America.

6.  (1866) A self-propelled aquatic missile shaped like a long cigar, which travels at speed and is detonated on impact with a ship.

• As with siren (see earlier post: Sirens) the greatest change from the original meaning occurred when it became a brand name.