impenetrable

Meanwhile, at the WCS facility, the waste will be covered by a 40-foot-thick layer of impenetrable red clay —which serves the same function as the salt at WIPP—once the storage sites are filled.

At the highest navigable point of the Congo River, thick jungle creates an impenetrable wall of green around a large island.

These reporters are working within a bubble, impenetrable to secular outsiders.

But, as Korda clearly recognizes, Lee himself could be almost as impenetrable as stone.

The Brazilian defense, touted as impenetrable in pre-tournament hype, proved to be bedraggled, and porous.

He had two hits for three official at-bats; yet afterward his solitary gloom was impenetrable.

The secret motives which actuate that mysterious woman are also impenetrable, but her fidelity is beyond a doubt.

He had been prepared for abuse, but not for impenetrable silence.

When under the influence of the latter feeling, his eye never failed to seek the visage of his dull and impenetrable kinsman.

But this is really all which is known; and the creation of the poems lies in impenetrable mystery.

So Olear sidled into the all but impenetrable underbrush and slowly, with infinite caution, wormed his way along.