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Synonyms

U-boat

American  
[yoo-boht] / ˈyuˌboʊt /

noun

  1. a German submarine.

U-boat British  

noun

  1. a German submarine, esp in World Wars I and II

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of U-boat

1910–15; < German U-Boot, short for Unterseeboot literally, undersea boat

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The first dog sled patrols began in eastern Greenland during World War II, when they discovered and helped destroy German weather stations, denying the Germans crucial information for their U-boat campaign in the Atlantic.

From Barron's • Jan. 28, 2026

The narrow Straits of Gibraltar was particularly harrowing for U-boat captains and crews.

From The Wall Street Journal • Nov. 7, 2025

But as happened elsewhere in the country, much of L.A.’s public German community went to ground after May 1915, when a German U-boat sank the British ocean liner Lusitania.

From Los Angeles Times • Aug. 8, 2025

The team's research involved going back to data from the time such as the U-boat commander's day journal which gave an indication of where it had been when it fired the torpedo.

From BBC • Aug. 15, 2024

The damage is light, mostly confined to the U-boat pens and refineries, but two errant bombs land in St. Pauli, a neighborhood known for its theaters and cafés and concert halls.

From "The Boy Who Dared" by Susan Campbell Bartoletti

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.