9 Grammatical Pitfalls


[im-pen-i-truh-buh l] /ɪmˈpɛn ɪ trə bəl/
not penetrable; that cannot be penetrated, pierced, entered, etc.
inaccessible to ideas, influences, etc.
incapable of being understood; inscrutable; unfathomable:
an impenetrable mystery.
Physics. possessing impenetrability.
Origin of impenetrable
late Middle English
1425-75; late Middle English impenetrabel < Latin impenetrābilis. See im-2, penetrable
Related forms
impenetrableness, noun
impenetrably, adverb
3. incomprehensible, mysterious, obscure, hidden.
3. clear, lucid. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for impenetrable
  • These weeds can develop dense, impenetrable stands that crowd out native plants.
  • The shoots collapse in mid to late summer, forming a dense, impenetrable mat of stems and leaves.
  • And there will be an element of resentment toward the author for making the subject matter of the book intentionally impenetrable.
  • But for me, in my impenetrable mantle, the safety was complete.
  • He followed the lady to her castle and ate voraciously of her supper, but was quite impenetrable to all her amorous advances.
  • The universe itself is an impenetrable mystery, yet it waits to be unraveled.
  • However, as effective as these measures are, no security system is impenetrable.
  • People often think of public art as being something that's abstract or impenetrable or something that's sort of imposed upon them.
  • Now press agents build impenetrable walls to guard the artist's myth.
  • The light-killing blackness makes for delicate balances of impenetrable gunk and infinite depth.
British Dictionary definitions for impenetrable


incapable of being pierced through or penetrated: an impenetrable forest
incapable of being understood; incomprehensible: impenetrable jargon
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
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

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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