im·​preg·​na·​ble im-ˈpreg-nə-bəl How to pronounce impregnable (audio)
: incapable of being taken by assault : unconquerable
an impregnable fortress
: unassailable
also : impenetrable
impregnable walls
impregnability noun
impregnableness noun
impregnably adverb

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."

Example Sentences

an impregnable fortress that had foiled one invader after another over the centuries the castle's supposedly impregnable walls
Recent Examples on the Web The San Gabriel Mountains loom like an impregnable fortress for millions of migrating birds making their long and perilous journey to distant breeding grounds in the far north. Louis Sahagún, Los Angeles Times, 17 Apr. 2023 But the kidnapping, essentially a small-time mix-up, puts him at odds with the Colombian army and their impregnable backers behind the curtain, the American military complex. Sam Sacks, WSJ, 16 Apr. 2021 The Samsung threat represented the first potential crack in Google’s seemingly impregnable search business, which was worth $162 billion last year. Nico Grant,, 16 Apr. 2023 The advertising department and the newsroom have an impregnable firewall. Cheryl Hall, Dallas News, 28 Feb. 2021 Set, at one day shy of 22, to become the youngest post-World War II champion, Pogacar flew on the penultimate stage, a lung-burning uphill time trial, and devoured the 57-second lead that had made Roglic look impregnable before the showdown in the mountains of eastern France., 19 Sep. 2020 The Titanic was the largest ocean liner in service at the time, thought to be nearly impregnable. CNN, 24 Apr. 2023 During World War II, while U.S. generals were parachuting onto battlefields with their troops and sharing their hardships, Soviet generals stayed far from the front and sent wave after wave of doomed conscripts against impregnable defenses. Yulia Latynina, WSJ, 1 May 2022 The halls of Congress are not impregnable. Jeff Sommer, New York Times, 8 Jan. 2021 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'impregnable.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English imprenable, from Middle French, from in- + prenable vulnerable to capture, from prendre to take — more at prize

First Known Use

15th century, in the meaning defined at sense 1

Time Traveler
The first known use of impregnable was in the 15th century


Dictionary Entries Near impregnable

Cite this Entry

“Impregnable.” Dictionary, Merriam-Webster, Accessed 1 Jun. 2023.

Kids Definition


im·​preg·​na·​ble im-ˈpreg-nə-bəl How to pronounce impregnable (audio)
: not able to be captured by assault : unconquerable
an impregnable fortress
impregnably adverb

More from Merriam-Webster on impregnable

Last Updated: - Updated example sentences
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