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impenetrable

[im-pen-i-truh-buh l] /ɪmˈpɛn ɪ trə bəl/
adjective
1.
not penetrable; that cannot be penetrated, pierced, entered, etc.
2.
inaccessible to ideas, influences, etc.
3.
incapable of being understood; inscrutable; unfathomable:
an impenetrable mystery.
4.
Physics. possessing impenetrability.
Origin of impenetrable
late Middle English
1425-1475
1425-75; late Middle English impenetrabel < Latin impenetrābilis. See im-2, penetrable
Related forms
impenetrableness, noun
impenetrably, adverb
Synonyms
3. incomprehensible, mysterious, obscure, hidden.
Antonyms
3. clear, lucid.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for impenetrable
Contemporary Examples
Historical Examples
  • “An impenetrable mystery” was sure “to hang for ever” as far as all mankind was concerned.

    The Secret Agent Joseph Conrad
  • Kirkwood smiled grimly, with a face of brass, impenetrable, inflexible.

    The Black Bag Louis Joseph Vance
  • Go not to the Alhambra: the fort is impenetrable—the guard faithful.

    Leila, Complete Edward Bulwer-Lytton
  • He had been prepared for abuse, but not for impenetrable silence.

    One Day's Courtship Robert Barr
  • Since then Tawabinisy had hidden himself behind his impenetrable grin.

    The Forest Stewart Edward White
British Dictionary definitions for impenetrable

impenetrable

/ɪmˈpɛnɪtrəbəl/
adjective
1.
incapable of being pierced through or penetrated: an impenetrable forest
2.
incapable of being understood; incomprehensible: impenetrable jargon
3.
incapable of being seen through: impenetrable gloom
4.
not susceptible to ideas, influence, etc: impenetrable ignorance
5.
(physics) (of a body) incapable of occupying the same space as another body
Derived Forms
impenetrability, noun
impenetrableness, noun
impenetrably, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for impenetrable
adj.

mid-15c., from Middle French impenetrable, from Latin impenetrabilis "that cannot be penetrated," from assimilated form of in- "not, opposite of" (see in- (1)) + penetrabilis "penetrable" (see penetrate). Related: Impenetrably; impenetrability.

Online Etymology Dictionary, © 2010 Douglas Harper
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Word Value for impenetrable

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