U-boat

noun3

1. •
   (historical) 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. •
   (slang) Nickname given to the General Electric Universal Series diesel-electric locomotives.