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
They have two great assets —impregnable mountains and magnificent harbours.
However strong the store may be, nothing would be really impregnable, and the stores would be most tempting targets for any wrongdoer.
They have gone into battle once a year, but the fortress has remained virtually impregnable.
The local authority would be placed in an impregnable position.
We had an impregnable bargaining card in that flat refusal.
I am going to put forward the view that in certain circumstances the fortress is not impregnable.
Whilst we all recognise the defects well enough, instinctively we regard the fortress as impregnable.
I do not think the right answer is to try to make all roads impregnable to cattle and sheep.
