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

Keep scrolling for more

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 That's according to one space scientist, who says Musk's plan could create an impenetrable wall of space junk around our planet. Fox News, "Elon Musk plots to put 30,000 more internet satellites into orbit as critics warn he’ll ‘trap humans on Earth’," 22 Oct. 2019 And yet the stories are frustratingly fragmented and incoherent — strange and impenetrable as the subconscious itself. Madeleine Kearns, National Review, "Zadie Smith’s New Short-Story Collection Dazzles and Disappoints," 26 Sep. 2019 Indiana’s defense was impenetrable and linebacker Cam Jones opened the second-half scoring by returning an interception 44 yards for a touchdown. San Diego Union-Tribune, "Hoosiers, Ramsey bounce back with 38-3 blowout over UConn," 21 Sep. 2019 The 32-year-old Martinez hits for power and average, is a good influence on the work ethic of younger teammates, and has created an impenetrable bubble to filter out the distractions that can come with playing in Boston., "Related: A closer look at Red Sox chief baseball officer Chaim Bloom," 5 Nov. 2019 The Hawkeyes stiffened after surrendering points on two straight drives by the Wolverines in the opening quarter, becoming as impenetrable as Wisconsin was during the first half of a 35-14 victory over Michigan on Sept. 21. Rainer Sabin, Detroit Free Press, "As spin cycle continues, Michigan football's offense remains far behind nation's elite," 8 Oct. 2019 Over recent seasons, Wolves' defence has been stellar and almost impenetrable at points., "Wolves Premier League Month in Review: August - Best Player, Worst Performance & Overall Rating," 8 Sep. 2019 The shrub, which displaces native plants with thickets impenetrable to wildlife, is a widespread noxious weed in the Pacific Northwest but is fairly new to New York. Washington Post, "Wags and weeds: Invasive plants meet match in detection dogs," 24 Aug. 2019 Although the series has been hailed by many critics and fans, others have found the material not only challenging but impenetrable. Greg Braxton,, "'Legion's' Noah Hawley wants to build you more than an emotional roller coaster," 24 June 2019

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.

See More

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

Keep scrolling for more

Learn More about impenetrable

Time Traveler for impenetrable

Time Traveler

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

See more words from the same century

Statistics for impenetrable

Last Updated

29 Nov 2019

Cite this Entry

“Impenetrable.” The Dictionary, Merriam-Webster Inc., Accessed 11 December 2019.

Keep scrolling for more

More Definitions for impenetrable


How to pronounce impenetrable (audio)

English Language Learners Definition of impenetrable

: impossible to pass or see through
: impossible to understand


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

Keep scrolling for more

Comments on impenetrable

What made you want to look up impenetrable? Please tell us where you read or heard it (including the quote, if possible).


heavy with or as if with moisture

Get Word of the Day daily email!

Test Your Vocabulary

Semantic Drift Quiz

  • a twisty river
  • Which of the following was once a synonym for fun?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!