impenetrable

adjective

im·​pen·​e·​tra·​ble (ˌ)im-ˈpe-nə-trə-bəl How to pronounce impenetrable (audio)
1
a
: incapable of being penetrated or pierced
b
: inaccessible to knowledge, reason, or sympathy : impervious
2
: incapable of being comprehended : inscrutable
impenetrably adverb

Examples of impenetrable in a Sentence

The fort's defenses were thought to be impenetrable. the ancient temple was surrounded by vast stretches of impenetrable jungle
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
And where leadership believes their infrastructure is impenetrable, red teams often walk through the front door with nothing more than confidence and a cover story. Jochen Schwenk, Forbes.com, 4 June 2025 To say that this film is impenetrable is an understatement. Sophie Monks Kaufman, IndieWire, 22 May 2025 Growing pressure Still, this spiritual shield is not impenetrable. Ogar Monday, Christian Science Monitor, 8 May 2025 But the paranoia of the missing papers was impenetrable. Ron Grossman, Chicago Tribune, 9 Mar. 2025 See All Example Sentences for impenetrable

Word History

Etymology

Middle English impenetrabel, from Middle French impenetrable, from Latin impenetrabilis, from in- + penetrabilis penetrable

First Known Use

15th century, in the meaning defined at sense 1a

Time Traveler
The first known use of impenetrable was in the 15th century

Browse Nearby Words

Cite this Entry

“Impenetrable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/impenetrable. Accessed 16 Jun. 2025.

Kids Definition

impenetrable

adjective
im·​pen·​e·​tra·​ble (ˈ)im-ˈpen-ə-trə-bəl How to pronounce impenetrable (audio)
1
: impossible to get through or into
impenetrable walls
impenetrable jungle
2
: impossible to understand
an impenetrable mystery
impenetrability
(ˌ)im-ˌpen-ə-trə-ˈbil-ət-ē
noun
impenetrably adverb

More from Merriam-Webster on impenetrable

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