impenetrable
adjective
im·pen·e·tra·ble
(ˌ)im-ˈpe-nə-trə-bəl 
1
a
: incapable of being penetrated or pierced
impenetrable armor
b
: inaccessible to knowledge, reason, or sympathy : impervious
an impenetrable heart
2
: incapable of being comprehended : inscrutable
an impenetrable mystery
Synonyms of impenetrable
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
Nate, on the other hand, just needed to show up in something simple but elevated (while honoring Jacob Elordi’s impenetrable Bottega Veneta contract), so he’s styled in a custom Bottega Veneta tuxedo.
—
Zoe Papelis, Vulture, 27 Apr. 2026
But the war has also shown that missile defenses are not impenetrable, with at least seven US service members killed by hostile action.
—Stephen Clark, ArsTechnica, 25 Apr. 2026
Completed in 1960, its diagrid exterior, clad in Portland stone, sought to blend in with the rest of the upscale Mayfair neighborhood while asserting itself as an impenetrable fortress.
—Rebecca Rose, Travel + Leisure, 24 Apr. 2026
This was one of the city's most impenetrable buildings, surrounded by armed guards, made to look uninviting and unappealing.
—Condé Nast, Condé Nast Traveler, 23 Apr. 2026
See All Example Sentences for impenetrable
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Zoe Papelis, Vulture, 27 Apr. 2026
But the war has also shown that missile defenses are not impenetrable, with at least seven US service members killed by hostile action.
—Stephen Clark, ArsTechnica, 25 Apr. 2026
Completed in 1960, its diagrid exterior, clad in Portland stone, sought to blend in with the rest of the upscale Mayfair neighborhood while asserting itself as an impenetrable fortress.
—Rebecca Rose, Travel + Leisure, 24 Apr. 2026
This was one of the city's most impenetrable buildings, surrounded by armed guards, made to look uninviting and unappealing.
—Condé Nast, Condé Nast Traveler, 23 Apr. 2026
See All Example Sentences for impenetrable
Cite this Entry
“Impenetrable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/impenetrable. Accessed 1 May. 2026.
Copy CitationKids Definition
impenetrable
adjective
im·pen·e·tra·ble
(ˈ)im-ˈpen-ə-trə-bəl
1
: impossible to get through or into
impenetrable walls
impenetrable jungle
2
: impossible to understand
an impenetrable mystery
impenetrability
noun
(ˌ)im-ˌpen-ə-trə-ˈbil-ət-ē
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