"The Enemy Below" attacker

• Vessel that's short for Unterseeboot
• Corvette's prey
• Wolf-pack member
• Undersea prowler
• "Das Boot" craft
• Menace in the 1957 film "The Enemy Below"
• Periscope's source
• Vessel included in the so-called "Plan Z"
• Erstwhile marine menace

Wikipedia Word definitions in Wikipedia
redirect U-boat