Ｕボート

noun

U-boat; submarine

Refers specifically to German submarines, especially from the World War eras. In Japanese, it is used as a loanword from English/German.

• 第だい一いち次じ世せ界かい大たい戦せん中ちゅう、ドイツのＵボートが多おおくの商しょう船せんを沈しずめた。

  During World War I, German U-boats sank many merchant ships.