Impervious and Impregnable

Impervious

Impervious adjective - Impossible to get through or into.
Usage example: the rain forest is impervious to all but the most dedicated explorers

Impregnable is a synonym for impervious in impermeable topic. In some cases you can use "Impregnable" instead an adjective "Impervious", when it comes to topics like impassible.

Nearby Word: imperviously

Impregnable

Impregnable adjective - Impossible to get through or into.
Usage example: the castle's supposedly impregnable walls

Impervious is a synonym for impregnable in impassible topic. You can use "Impervious" instead an adjective "Impregnable".

Cite this Source
Impregnable and Impervious. (2016). Retrieved 2026, August 15, from https://thesaurus.plus/related/impervious/impregnable
Impervious & Impregnable. N.p., 2016. Web. 15 Aug. 2026. <https://thesaurus.plus/related/impervious/impregnable>.
Impregnable or Impervious. 2016. Accessed August 15, 2026. https://thesaurus.plus/related/impervious/impregnable.
Google Ngram Viewer shows how "impervious" and "impregnable" have occurred on timeline