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
France believed its Maginot Line of fortresses was impregnable – until the Germans simply went around it.
—
New Atlas, 19 Feb. 2026
South Africa’s racist system of Apartheid endured for generations and, so brutally was it maintained, appeared impregnable.
—Matthew Carey, Deadline, 16 Feb. 2026
By now, Bondi’s playbook at these hearings is both familiar and seemingly impregnable.
—Ruth Marcus, New Yorker, 12 Feb. 2026
Which explains couldn’t: if Meta had ever been a monopoly, there’s no way its shareholders would have ever allowed $70 billion in new spending meant to expand an already impregnable moat.
—John Tamny, Forbes.com, 21 Jan. 2026
See All Example Sentences for impregnable
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New Atlas, 19 Feb. 2026
South Africa’s racist system of Apartheid endured for generations and, so brutally was it maintained, appeared impregnable.
—Matthew Carey, Deadline, 16 Feb. 2026
By now, Bondi’s playbook at these hearings is both familiar and seemingly impregnable.
—Ruth Marcus, New Yorker, 12 Feb. 2026
Which explains couldn’t: if Meta had ever been a monopoly, there’s no way its shareholders would have ever allowed $70 billion in new spending meant to expand an already impregnable moat.
—John Tamny, Forbes.com, 21 Jan. 2026
See All Example Sentences for impregnable
Cite this Entry
“Impregnable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/impregnable. Accessed 7 Mar. 2026.
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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