impenetrable
Americanadjective
-
not penetrable; that cannot be penetrated, pierced, entered, etc.
-
inaccessible to ideas, influences, etc.
-
incapable of being understood; inscrutable; unfathomable.
an impenetrable mystery.
- Synonyms:
- hidden, obscure, mysterious, incomprehensible
-
Physics. possessing impenetrability.
adjective
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incapable of being pierced through or penetrated
an impenetrable forest
-
incapable of being understood; incomprehensible
impenetrable jargon
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incapable of being seen through
impenetrable gloom
-
not susceptible to ideas, influence, etc
impenetrable ignorance
-
physics (of a body) incapable of occupying the same space as another body
Other Word Forms
Etymology
Origin of impenetrable
1425–75; late Middle English impenetrabel < Latin impenetrābilis. See im- 2, penetrable
Explanation
Impenetrable describes something that's impossible to get through. Whether it's a brick wall or a difficult reading passage, something impenetrable won't let you in. Impenetrable comes from the Latin impenetrabilis, meaning "not to put or get into, enter into." Impenetrable, the adjective, has two meanings. When you're trying to learn a subject that is so complicated, so confusing or so detailed that it seems like it's in another language or from another planet, it's impenetrable — like calculus. Or a physical object can be impenetrable, meaning it is impossible to actually enter or get inside of, like that impenetrable nightclub that has bouncers watching every entrance to keep you and your friends out.
Vocabulary lists containing impenetrable
The Diary of Anne Frank
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The Alchemist
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Tolkien Reading Day, List 1
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
She’s everything I wasn’t and never would be: aggressively pink, fluffy and wrapped in an impenetrable privilege that appeared to reward her ditziness.
From Salon • Jul. 6, 2026
The production also had problems with the ground being impenetrable.
From BBC • May 23, 2026
He kept about him a reserve that, the author admits, was like “an impenetrable wall.”
From The Wall Street Journal • May 20, 2026
The building of the case is well done but what’s most memorable is the impenetrable brick wall of denial constructed by Shirilla’s family and friends in the face of that evidence.
From Los Angeles Times • May 18, 2026
It looms before us like an impenetrable wall, trying to crush us, but not yet able to.
From "The Diary of a Young Girl" by Anne Frank
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
