1
as in dense
impossible to get through or into
the ancient temple was surrounded by vast stretches of impenetrable jungle
Synonyms & Similar Words
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Antonyms & Near Antonyms
2
as in mysterious
being beyond one's powers to know, understand, or explain
the mysteries of that religion are completely impenetrable to outsiders
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3
as in incomprehensible
impossible to understand
the textbook's language is completely impenetrable, at least to me
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4
as in tight
not allowing penetration (as by gas, liquid, or light)
the container of toxic waste has an impenetrable seal to prevent leaks
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Example Sentences
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Recent Examples of impenetrable
In a refreshing departure from so many impenetrable Marvel series past, creators Deston Daniel Cretton and Andrew Guest expediently fill in viewers on the essential points of Trevor’s backstory.
—
Judy Berman, Time, 26 Jan. 2026
Right now, though, Payton is betting he’s built a fortress impenetrable to such thoughts as long as there is still an opponent ahead.
—Parker Gabriel, Denver Post, 24 Jan. 2026
BitLocker’s encryption algorithms have proven impenetrable to prior law enforcement attempts to break in, according to a Forbes review of historical cases.
—Thomas Brewster, Forbes.com, 23 Jan. 2026
All night, the fog had stubbornly hidden the stars in the dark, impenetrable sky, but now the sliver of light widened little by little into a luminous band, a hazy phosphorescence that slowly spread and took over.
—Literary Hub, 22 Jan. 2026
See All Example Sentences for impenetrable
Judy Berman, Time, 26 Jan. 2026
Right now, though, Payton is betting he’s built a fortress impenetrable to such thoughts as long as there is still an opponent ahead.
—Parker Gabriel, Denver Post, 24 Jan. 2026
BitLocker’s encryption algorithms have proven impenetrable to prior law enforcement attempts to break in, according to a Forbes review of historical cases.
—Thomas Brewster, Forbes.com, 23 Jan. 2026
All night, the fog had stubbornly hidden the stars in the dark, impenetrable sky, but now the sliver of light widened little by little into a luminous band, a hazy phosphorescence that slowly spread and took over.
—Literary Hub, 22 Jan. 2026
See All Example Sentences for impenetrable
Recent Examples of Synonyms for impenetrable
Adjective
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For years, astronomers have debated whether planets this massive could form through core accretion, the slow, bottom-up process in which solid material clumps together into a dense core that then pulls in vast amounts of gas.—
Samantha Mathewson,
Space.com,
10 Feb. 2026
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In Earth’s deep interior and under enormous pressure, a dense, hot and fluid metal core began to churn.—
Mindy Weisberger,
CNN Money,
10 Feb. 2026
Adjective
-
For several months, a mysterious sign displayed in the windows of vacant storefront in Shorewood has intrigued passersby along Capitol Drive.—
Claudia Levens,
jsonline.com,
10 Feb. 2026
-
To anyone who's gotten a bill three months after treatment only to find mysterious charges, the idea seemed intuitive.—
Darius Tahir,
NPR,
10 Feb. 2026
Adjective
-
Even seemingly outlandish and incomprehensible claims called in to tip lines were examined.—
Arkansas Online,
Arkansas Online,
9 Feb. 2026
-
Even seemingly outlandish and incomprehensible claims, called in to tip lines, were examined.—
Michael R. Sisak,
Fortune,
8 Feb. 2026
Adjective
-
The massacre prompted a national reckoning about violence against women and led to tighter gun laws.—
Lex Harvey,
CNN Money,
11 Feb. 2026
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However, despite workers’ noticeable preference for remote positions, the demands of employers and a much tighter job market suggest many may need to adjust to the new realities of the marketplace.—
Victoria Baeza Garcia,
Dallas Morning News,
10 Feb. 2026
Adjective
-
There have been concussions, and the right knee seemingly impervious to staying healthy.—
Will Graves,
Twin Cities,
8 Feb. 2026
-
Opponents said McLean’s plan would cut down 17 acres of trees and add 7 acres of impervious surfaces, worsening the periodic flooding that’s already a concern.—
Don Stacom,
Hartford Courant,
23 Jan. 2026
Adjective
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At the end of the video, Swift shows a clip from their appearance on the Graham Norton Show in which Gleeson jokes about wanting to star in a music video and Swift giving a surprised, but cryptic smile.—
Lexy Perez,
HollywoodReporter,
6 Feb. 2026
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Bryony hopes that sharing her story will help spread awareness about cryptic pregnancies, or stealth pregnancies.—
Sam Gillette,
PEOPLE,
29 Jan. 2026
Adjective
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Despite being grouped together under the Miao umbrella, the four groups have little in common today, and their languages are different enough as to be unintelligible between groups.—
Meredith Kile,
PEOPLE,
31 Jan. 2026
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Transcribers often complained that the wax recordings were unintelligible—dictators needed to speak directly into the speaking tube, loudly, clearly, and at an appropriate pace, but many did not.—
IEEE Spectrum,
IEEE Spectrum,
6 Jan. 2026
Adjective
-
The impermeable seed coat strategy generally helps survival of the species by making sure all of a season’s crop don’t germinate in the same year.—
Paul Cappiello,
Louisville Courier Journal,
21 Nov. 2025
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The discovery could enable large-scale use of impermeable coatings once limited by graphene’s scalability issues.—
Aamir Khollam,
Interesting Engineering,
12 Nov. 2025
Cite this Entry
“Impenetrable.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/impenetrable. Accessed 14 Feb. 2026.
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