0 A building or other place that is impregnable is so strongly built and/or defended that it cannot be entered by force: --
1 so strongly made that it cannot be broken into or taken by force: --
an impregnable fortress
I said just now that the finance of this country stood out like an impregnable rock in the middle of the sea.
Indeed, the result of constant and consistent pressure from external sources is that the system becomes almost impregnable.
There is no prison that is impregnable to the slyness, the cleverness and the potential of the revolutionaries.
Are those industries so impregnable that a little adjustment here or there may not do them harm?
I am quite ready to admit that it should be the duty of us all to render our country impregnable to attack.
In this country at least we are impregnable.
I have already made known my own view that total, impregnable security is not compatible with the free society we enjoy.
I do not think the right answer is to try to make all roads impregnable to cattle and sheep.
