impenetrable

play

adjective im·pen·e·tra·ble \ (ˌ)im-ˈpe-nə-trə-bəl \

Definition of impenetrable

1 a :incapable of being penetrated or pierced

b :inaccessible to knowledge, reason, or sympathy :impervious

2 :incapable of being comprehended :inscrutable

—

impenetrably

play \(ˌ)im-ˈpe-nə-trə-blē\ adverb

See impenetrable defined for English-language learners

See impenetrable defined for kids

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 of impenetrable from the Web

Slate isn't interested in being impenetrable or a Hollywood cipher, and her warmth and genuine relatability draw in fans who see her as an imaginary celebrity bestie.

— nojan aminosharei, Marie Claire, "Jenny Slate Is Trying Not to Overshare," 1 Aug. 2017
Even so, the virtually impenetrable barrier of the Himalayas has generally allowed the rivals to agree to disagree.

— The Economist, "One Lifebelt, One RoadChina makes Pakistan an offer it cannot refuse," 22 July 2017
The lecture proposed to explain why oak forests were replaced by pine forests when cut down and vice versa— a phenomenon Emerson, Horace Greeley, and many other reasonably informed observers considered an impenetrable mystery.

— Longreads, "Late in Life, Thoreau Became a Serious Darwinist," 13 July 2017
During his campaign, the president vowed to build an impenetrable wall along the length of the U.S.-Mexican border out of concrete and steel.

— darlene superville, The Seattle Times, "Trump sits down with Mexico’s president at last," 7 July 2017
During his campaign, the president vowed to build an impenetrable wall along the length of the U.S.-Mexican border out of concrete and steel.

— darlene superville, The Seattle Times, "Trump sits down with Mexico’s president at last," 7 July 2017
The species barrier, though formidable, was not impenetrable.

— john fauber, Milwaukee Journal Sentinel, "A family of fatal brain diseases has baffled scientists while infecting new species," 6 July 2017
Hildebrandt was impenetrable and gave Cincinnati one of its best sporting moments in recent history.

— patrick brennan and charlie hatch, Cincinnati.com, "Debate: The best single-game performance in FC Cincy history," 6 July 2017
Replace the Xbox controller maybe with the impenetrable machinations of Congress, where bills and markups and votes are often the stuff of hard-to-discern theater.

— vanityfair.com, "The “WTF” Plan to Disrupt Politics Is Everything That’s Wrong with Silicon Valley," 5 July 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.