u-boat

noun

• (military, nautical, historical) Any German submarine of the First or Second World War, or any Austro-Hungarian submarine of the First World War.
• 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.
• (rail transport, slang) Nickname given to the General Electric Universal Series diesel-electric locomotives.