impenetrable

adjective
im·​pen·​e·​tra·​ble | \ (ˌ)im-ˈpe-nə-trə-bəl How to pronounce impenetrable (audio) \

Definition of impenetrable

1a : incapable of being penetrated or pierced
b : inaccessible to knowledge, reason, or sympathy : impervious
2 : incapable of being comprehended : inscrutable

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Other Words from impenetrable

impenetrably \ (ˌ)im-​ˈpe-​nə-​trə-​blē How to pronounce impenetrably (audio) \ 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

They’re seen instead as impenetrable black boxes where our most intimate personal secrets are bought and sold to further fatten a shadowy Über-class of obscene wealth and privilege trading behind velvet ropes in elite cryptocurrencies. Jon Talton, The Seattle Times, "Another bite of the Apple: Beyond that trillion-dollar valuation," 7 Aug. 2018 This is the only team on this list to not win its bowl game, but Alabama had been impenetrable prior to its final two games of 2013. Will Mccollister, SI.com, "On the Outside Looking In: The Best Teams to Finish No. 3 in the BCS Era," 11 July 2018 End-to-end encryption means that the message is impenetrable to everyone — including the app vendor and the network provider — except the message sender and receiver. Barbara Krasnoff, The Verge, "What is RCS and why you might want it," 12 Dec. 2018 Drones are amazing and cool and powerful, but traditionally they can be thwarted by an impenetrable obstacle that has vexed drone creators and pilots for years: doors. David Grossman, Popular Mechanics, "Inspired by Wasps, This Micro-Drone Lifts 40 Times its Weight," 25 Oct. 2018 In the end, there was nothing del Potro could do to break down Djokovic, the most impenetrable man in tennis. Tom Perrotta, WSJ, "Novak Djokovic Wins the U.S. Open," 9 Sep. 2018 Despite the seemingly impenetrable wall put up around Lovato, the substances — and the seedy people — sneaked in. Fox News, "Demi Lovato reportedly surrounded herself with enablers prior to overdose," 5 Aug. 2018 Pondering the impenetrable fog of the early universe. Lacy Schley, Discover Magazine, "Staring Into the Abyss," 24 Nov. 2018 He is protected by an impenetrable and ever-present armor of enthusiasm that has helped him endure any setback, letdown or underestimation. Kayleigh Roberts, Marie Claire, "Taylor Swift (Kind of) Came Out of Hiding to Praise BFF Ed Sheeran," 20 Apr. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'impenetrable.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of impenetrable

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

History and Etymology for impenetrable

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

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Last Updated

8 Feb 2019

Look-up Popularity

Time Traveler for impenetrable

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

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More Definitions for impenetrable

impenetrable

adjective

English Language Learners Definition of impenetrable

: impossible to pass or see through
: impossible to understand

impenetrable

adjective
im·​pen·​e·​tra·​ble | \ im-ˈpe-nə-trə-bəl How to pronounce impenetrable (audio) \

Kids Definition of impenetrable

1 : impossible to pass through or see through impenetrable walls impenetrable darkness
2 : impossible to understand an impenetrable mystery

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