U-boat /ūˈbōt or (German) ooˈ/

A German submarine

• kexes
• key
• keyboard
• keyboarded
• keyboarder
• keyboarders
• keyboarding
• keyboardist
• keyboardists
• keyboards
• keybugle
• keybugles
• keycard
• keycards
• key-cold
• key-desk
• key-desks
• keyed
• keyed bugle
• keyed bugles
• key-fruit
• key-fruits
• key grip
• key grips
• keyhole