UK:*UK and possibly other pronunciationsUK and possibly other pronunciations/ɪmˈpɛnɪtrəbəl/US:USA pronunciation: IPA and respellingUSA pronuncation: IPA/ɪmˈpɛnɪtrəbəl/ ,USA pronunciation: respelling(im peni trə bəl)

WordReference Random House Learner's Dictionary of American English © 2020
im•pen•e•tra•ble /ɪmˈpɛnɪtrəbəl/USA pronunciation   adj. 
  1. that cannot be penetrated:an impenetrable barrier.
  2. that cannot be understood:an impenetrable mystery.
im•pen•e•tra•bil•i•ty /ɪmˌpɛnɪtrəˈbɪlɪti/USA pronunciation  n. [uncountable]
im•pen•e•tra•bly,  adv.

WordReference Random House Unabridged Dictionary of American English © 2020
im•pen•e•tra•ble  (im peni trə bəl),USA pronunciation adj. 
  1. not penetrable;
    that cannot be penetrated, pierced, entered, etc.
  2. inaccessible to ideas, influences, etc.
  3. incapable of being understood;
    unfathomable:an impenetrable mystery.
  4. Physicspossessing impenetrability.
im•pene•tra•ble•ness, n. 
  • Latin impenetrābilis. See im-2, penetrable
  • late Middle English impenetrabel 1425–75
    • 3.See corresponding entry in Unabridged incomprehensible, mysterious, obscure, hidden.
    • 3.See corresponding entry in Unabridged clear, lucid.

Collins Concise English Dictionary © HarperCollins Publishers::
impenetrable /ɪmˈpɛnɪtrəbəl/ adj
  1. incapable of being pierced through or penetrated: an impenetrable forest
  2. incapable of being understood; incomprehensible
  3. incapable of being seen through: impenetrable gloom
  4. not susceptible to ideas, influence, etc: impenetrable ignorance
  5. (of a body) incapable of occupying the same space as another body

imˌpenetraˈbility n imˈpenetrableness n imˈpenetrably adv
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