impregnable

The front door looked impregnable, but a side window was open.

The city was built for defense, and with very little work could be made impregnable.

In my hands, who knows what might not be made of this impregnable place?

"They have developed some sort of air defense system that is impregnable."

The ship had become their world, and it was very nearly impregnable.

The last thing he wanted at that moment was for those impregnable doors to open!

These soon made their defenses in that part of the country impregnable.

"Now we are on either side of an impregnable barrier."

It was wise to have a second line of defense even when the first seemed impregnable.

That looks a pretty impregnable base for the next advance.

Her innocence would be impregnable; she had nothing to fear.

It is said to be impregnable, as I am sure you already know."

I saw that his position on the old parchment was impregnable.

It was quite evidently impregnable to any but attack by air.

We may have been too ready to assume that our island is impregnable.

Perhaps because the national ocean liner felt so very impregnable.

Finding that this new position also was impregnable he again retired.

When the defenses were finished in 1756, the city was considered impregnable.

But they know what it is to be part of a magic and impregnable circle.

He is a monster, impregnable to any weapon we now can use against him.

Elephant Pass was thought to be an impregnable military complex.

They did not want to waste their time, effort, money and future chances in taking on an impregnable President.

His house resembled a fortress which had been made impregnable.

"The shelters are impregnable; this is what they were built for."

The scientists who made the base impregnable now have to figure a way to enter it.