Impregnable
Impregnable adjective - Immune to attack; incapable of being tampered with.
Usage example: an impregnable fortress
Strong is a synonym for impregnable in invulnerable topic. In some cases you can use "Strong" instead an adjective "Impregnable", when it comes to topics like property, fast, unyielding, resistant.
Mutual synonyms
Related pairs
Both words in one sentence
- O how shall summer's honey breath hold out Against the wrackful siege of batt'ring days, When rocks impregnable are not so stout, Nor gates of steel so strong but time decays?
Source: True Art Is Ancient -
Aramon tactics generally revolve around building an impregnable fortress that could fend off any threat long before they could even get close while building a strong army in the background to crush the remainders with.
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Only 5,000 strong, they routinely destroyed much larger forces with few casualties, culminating when they defeated a force of 30,000 supposedly "elite" enemy knights fortified in a castle known for being impregnable.
Source: Elite Army
Cite this Source
Strong and Impregnable. (2016). Retrieved 2026, August 16, from https://thesaurus.plus/related/impregnable/strong
Impregnable & Strong. N.p., 2016. Web. 16 Aug. 2026. <https://thesaurus.plus/related/impregnable/strong>.
Strong or Impregnable. 2016. Accessed August 16, 2026. https://thesaurus.plus/related/impregnable/strong.
Google Ngram Viewer shows how "impregnable" and "strong" have occurred on timeline