impenetrable
/ɪmˈpɛnətɹəbəl/ adjective C1- Not penetrable. · The fortress is impenetrable, so it cannot be taken.
- Opaque; obscure; not translucent or transparent.
- Incomprehensible; fathomless; inscrutable. · Business jargon makes this document impenetrable—I can’t understand it.
From the library
The stubborn spearsmen still made good Their dark impenetrable wood,
Yet he did not leave a foot of this granite wall, as impenetrable as futurity, without strict scrutiny; he did not see a fissure without introducing the blade of his hunting sword into it, or a projecting point on which he did not lean and press in the hopes it would give way.
“There are two lines of old yew hedge, twelve feet high and impenetrable.
As I focus my mind upon it, it seems rather less impenetrable.
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