[ 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
SYNONYMS FOR impenetrable
ANTONYMS FOR impenetrable
Related formsim·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 impenetrably

British Dictionary definitions for impenetrably


/ (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 Formsimpenetrability, 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

Word Origin and History for impenetrably



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