Impenetrable
adj, noun ·Common ·High school level
Definitions
- 1 A person not openly given to friendship.
"I should lose the reputation that I am gradually acquiring among our impenetrables here, were I to confess the excitement which I felt at the idea of entering his house—the house of that great general under whose command you made your first charge."
- 1 Not penetrable. not-comparable
"The fortress is impenetrable, so it cannot be taken."
- 2 Opaque; obscure; not translucent or transparent. not-comparable
"When night falls, she cloaks the world in impenetrable darkness."
- 3 Incomprehensible; fathomless; inscrutable. figuratively, not-comparable
"Business jargon makes this document impenetrable—I can’t understand it."
- 1 impossible to understand wordnet
- 2 not admitting of penetration or passage into or through wordnet
- 3 permitting little if any light to pass through because of denseness of matter wordnet
Example
More examples"Tom stared into the impenetrable blackness of the night sky."
Etymology
From Middle English inpenetrabel, inpenetrabyle, from Middle French impenetrable or directly from its etymon, Latin impenetrābilis. By surface analysis, im- + penetrable.
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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.