im·​preg·​na·​ble | \ im-ˈpreg-nə-bəl How to pronounce impregnable (audio) \

Definition of impregnable

1 : incapable of being taken by assault : unconquerable an impregnable fortress
2 : unassailable also : impenetrable impregnable walls

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Other Words from impregnable

impregnability \ (ˌ)im-​ˌpreg-​nə-​ˈbi-​lə-​tē How to pronounce impregnable (audio) \ noun
impregnableness \ im-​ˈpreg-​nə-​bəl-​nəs How to pronounce impregnable (audio) \ noun
impregnably \ im-​ˈpreg-​nə-​blē How to pronounce impregnable (audio) \ adverb

Did You Know?

Since the days when the Norman French ruled England, English-speakers have been captured by the allure of French terms. Impregnable is one of the many English words that bear a French ancestry. 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.

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 What should have been an impregnable fortress on a day when this country's most important leaders were gathered to certify an election was exposed as being almost comically easy to crack. Star Tribune, "Focus on restraining Trump until he's gone," 7 Jan. 2021 The moat wasn't meant to be impregnable, but rather to slow down an attacker and give the defender time to prepare. Kyle Mizokami, Popular Mechanics, "Medieval Star Forts Are Surprisingly Alive and Well in North Africa," 31 Dec. 2020 This last assertion may seem overstated—the British Empire was, after all, a vast and impregnable place in the first decade of the 20th century, when Dhammaloka was at his militant peak. Tunku Varadarajan, WSJ, "‘The Irish Buddhist’ Review: Monk on a Mission," 27 Dec. 2020 The former official said criticism from conservative talk show host Rush Limbaugh showed how Trump’s once impregnable GOP base was cracking. Noah Bierman, Los Angeles Times, "For Trump, it’s all over but the tweeting," 24 Nov. 2020 The valuations of target companies then explode, too, but street-level investors, once again, are shut out of these stratospheric early gains, which flow to the same impregnable oligarchy. Rana Dasgupta, Harper's Magazine, "The Silenced Majority," 24 Nov. 2020 Neither dominates nationally, even as one or the other enjoys impregnable dominance in many states. Steve Chapman,, "Column: Our long national nightmare is not over," 4 Nov. 2020 Taiwan, once considered impregnable, is slowly, but surely becoming more vulnerable to attack. Kyle Mizokami, Popular Mechanics, "The U.S. May Soon Sell Taiwan Missiles to Strike China," 29 Oct. 2020 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, "Fiction: A Perpetual Battlefield," 9 Oct. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'impregnable.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of impregnable

15th century, in the meaning defined at sense 1

History and Etymology for impregnable

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

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Time Traveler for impregnable

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

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Last Updated

31 Jan 2021

Cite this Entry

“Impregnable.” Dictionary, Merriam-Webster, Accessed 26 Feb. 2021.

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More Definitions for impregnable



English Language Learners Definition of impregnable

: not able to be captured by attack : very strong
: not likely to be weakened or changed


im·​preg·​na·​ble | \ im-ˈpreg-nə-bəl How to pronounce impregnable (audio) \

Kids Definition of impregnable

: not able to be captured by attack : unconquerable

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