impregnable
adjective
im·preg·na·ble
im-ˈpreg-nə-bəl 
1
: incapable of being taken by assault : unconquerable
an impregnable fortress
2
Did you know?
Impregnable is one of the many English words that bear a French ancestry, thanks to the Norman conquest of England in 1066. It derives from the Middle French verb prendre, which means "to take or capture." Combining prendre with various prefixes has given our language many other words, too, including surprise, reprise, and enterprise. Remarkably, impregnable has a different origin from the similar-looking word pregnant; that word comes from a different Latin word, praegnas, meaning "carrying a fetus."
Examples of impregnable in a Sentence
an impregnable fortress that had foiled one invader after another over the centuries
the castle's supposedly impregnable walls
Recent Examples on the Web
One of the grandest occasions in golf was in 1930, when the great Bobby Jones won the British Amateur at St. Andrews and then captured the claret jug at Royal Liverpool on his way to winning the Grand Slam of that era — the impregnable quadrilateral, as it was called.
—
Doug Ferguson, Chicago Tribune, 16 July 2025
The film starts on the morning of February 17 2003, when detectives from Antwerp’s infamous ‘Diamond Squad’ were called to investigate the night-time robbery of an allegedly impregnable vault in the middle of the Belgian city, which is nicknamed the City of Diamonds.
—Max Goldbart, Deadline, 16 July 2025
Needless to say, Superman regains his identity in time for a final assault on a supposedly impregnable computer designed by Pryor and manned by Vaughn and his formidable sister (Annie Ross), and hidden away somewhere in the Grand Canyon.
—Arthur Knight, HollywoodReporter, 7 July 2025
As a result, homeowners and developers are reconsidering their approach to luxury living, emphasizing fire-resistant materials, impregnable landscaping, and cutting-edge smart-home technologies.
—Abby Montanez, Robb Report, 6 July 2025
See All Example Sentences for impregnable
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Doug Ferguson, Chicago Tribune, 16 July 2025
The film starts on the morning of February 17 2003, when detectives from Antwerp’s infamous ‘Diamond Squad’ were called to investigate the night-time robbery of an allegedly impregnable vault in the middle of the Belgian city, which is nicknamed the City of Diamonds.
—Max Goldbart, Deadline, 16 July 2025
Needless to say, Superman regains his identity in time for a final assault on a supposedly impregnable computer designed by Pryor and manned by Vaughn and his formidable sister (Annie Ross), and hidden away somewhere in the Grand Canyon.
—Arthur Knight, HollywoodReporter, 7 July 2025
As a result, homeowners and developers are reconsidering their approach to luxury living, emphasizing fire-resistant materials, impregnable landscaping, and cutting-edge smart-home technologies.
—Abby Montanez, Robb Report, 6 July 2025
See All Example Sentences for impregnable
Cite this Entry
“Impregnable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/impregnable. Accessed 1 Aug. 2025.
Copy CitationKids Definition
impregnable
adjective
im·preg·na·ble
im-ˈpreg-nə-bəl
: not able to be captured by assault : unconquerable
an impregnable fortress
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