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
The building of the case is well done but what’s most memorable is the impenetrable brick wall of denial constructed by Shirilla’s family and friends in the face of that evidence.
—
Stuart Miller, Los Angeles Times, 18 May 2026
Rake grounds into the upper soil layer to avoid creating an impenetrable mat on the soil surface.
—Kim Toscano, Southern Living, 17 May 2026
When faced with a unified, impenetrable front that raises the geopolitical costs of his disruption, Trump simply moves on.
—Jeffrey Sonnenfeld, Time, 11 May 2026
Elite defenses have increasingly tested and thwarted Denver’s once-impenetrable two-man game in the playoff moments that often steer front offices in their decision-making.
—Bennett Durando, Denver Post, 1 May 2026
See All Example Sentences for impenetrable
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Stuart Miller, Los Angeles Times, 18 May 2026
Rake grounds into the upper soil layer to avoid creating an impenetrable mat on the soil surface.
—Kim Toscano, Southern Living, 17 May 2026
When faced with a unified, impenetrable front that raises the geopolitical costs of his disruption, Trump simply moves on.
—Jeffrey Sonnenfeld, Time, 11 May 2026
Elite defenses have increasingly tested and thwarted Denver’s once-impenetrable two-man game in the playoff moments that often steer front offices in their decision-making.
—Bennett Durando, Denver Post, 1 May 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 22 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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