U-boat

Etymology
.

Noun

 * 1)  Any German submarine of the First or Second World War, or any Austro-Hungarian submarine of the First World War.
 * 2) A narrow, utility cart with tall handles on both ends that is used to carry loads of retail products to be sold, so named because its shape is roughly that of a capital U.
 * 3)  Nickname given to the General Electric Universal Series diesel-electric locomotives.