[ im-pen-i-truh-buhl ]
/ 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

1425–75; late Middle English impenetrabel < Latin impenetrābilis. See im-2, penetrable

OTHER WORDS FROM impenetrable

im·pen·e·tra·ble·ness, nounim·pen·e·tra·bly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for impenetrable

British Dictionary definitions for impenetrable

/ (ɪmˈpɛnɪtrəbəl) /


incapable of being pierced through or penetratedan impenetrable forest
incapable of being understood; incomprehensibleimpenetrable jargon
incapable of being seen throughimpenetrable gloom
not susceptible to ideas, influence, etcimpenetrable ignorance
physics (of a body) incapable of occupying the same space as another body

Derived forms of impenetrable

impenetrability, nounimpenetrableness, nounimpenetrably, 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