im·​pen·​e·​tra·​ble (ˌ)im-ˈpe-nə-trə-bəl How to pronounce impenetrable (audio)
: incapable of being penetrated or pierced
: inaccessible to knowledge, reason, or sympathy : impervious
: 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 Look closely, and the blackness, visually impenetrable but strangely soft, has been achieved by applying Rothko-like veils of layered pigment. Christopher Knight, Los Angeles Times, 9 Nov. 2023 Meanwhile, the average American has run into a high cost of living, impenetrable housing market, and massive student loans. Bychloe Berger, Fortune, 14 Nov. 2023 Last Night testifies to its director’s dexterity with constructing subtly meaningful moments, but without more insight into its protagonist, the film can feel unintentionally impenetrable at times. Lovia Gyarkye, The Hollywood Reporter, 29 Sep. 2023 What’s impenetrable about the stock market — the manipulations, the rule-changing, the clandestine deals — is made crystal-clear. Robert Abele, Los Angeles Times, 15 Sep. 2023 The Cardinals’ defense is not some impenetrable force. Gary Klein, Los Angeles Times, 17 Oct. 2023 Some celebrities like to keep their leather coats in Matrix territory, with severe styling: Kendall Jenner and Anya Taylor-Joy rocked black leather coats with impenetrable black shades. Hannah Jackson, Vogue, 16 Oct. 2023 Once an impenetrable jungle, Panama's Darién Gap is seeing large numbers of U.S.-bound Venezuelan migrants cross its rugged and roadless terrain each month. Camilo Montoya-Galvez, CBS News, 26 Sep. 2023 But in fact an unease remained, which grew and which was our mother’s impenetrable bequest to us. Rachel Cusk, Harper's Magazine, 10 Sep. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'impenetrable.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Dictionary Entries Near impenetrable

Cite this Entry

“Impenetrable.” Dictionary, Merriam-Webster, Accessed 9 Dec. 2023.

Kids Definition


im·​pen·​e·​tra·​ble (ˈ)im-ˈpen-ə-trə-bəl How to pronounce impenetrable (audio)
: impossible to get through or into
impenetrable walls
impenetrable jungle
: impossible to understand
an impenetrable mystery
impenetrably adverb

More from Merriam-Webster on impenetrable

Last Updated: - Updated example sentences
Love words? Need even more definitions?

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