Sentence examples similar to impregnable summary from inspiring English sources

An impregnable theory, or one nearing the limit of impregnability, is in fact as great an absurdity as an impregnable armour-plate.

An impregnable assertion.

The summary states: "The recommendations clearly articulate the lack of FP [Force Protection] resources in certain key areas of the airfield, countering the media's assertion that Camp Bastion was impregnable.

Is that defence impregnable?

The enigma seems impregnable.

"Bell Canada is impregnable".

To many, Google appears impregnable.

The Confederate entrenchment was impregnable.

The death penalty seemed impregnable.

"Impregnable" was an autoantonym, too.

No system, however, is impregnable.