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."

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 Hitler's combat engineers have given evidence that the impregnable fort of yesterday is today just another target for superior offensive weapons. Ashraya Gupta, Scientific American, 7 Sep. 2023 Thanks to its impregnable intake plumbing, the LM002's V-12 is relatively hushed, with the dual exhaust's crispy cackle dominating the soundtrack. Ezra Dyer, Car and Driver, 4 Sep. 2023 Bonucci was part of the fabled ‘BBC’ back line alongside Andrea Barzagli and Giorgio Chiellini that, with Gianluigi Buffon in support just behind, was near impregnable. Emmet Gates, Forbes, 17 July 2023 Those barriers are not impregnable, however, as logic and history make clear. G. John Ikenberry, Foreign Affairs, 11 Feb. 2022 The Titanic was the largest ocean liner in service at the time, thought to be nearly impregnable. Jack Guy, CNN, 31 May 2023 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 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 29 Sep. 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

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