Impregnability is a synonym of unbeatability.
As nouns the difference between impregnability and unbeatability
is that impregnability is the quality or state of being impregnable; invincibility while unbeatability is the quality of being unbeatable, undefeatability.
impregnability
English
Noun
(-)
The quality or state of being impregnable; invincibility.
References
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unbeatability
English
Noun
(-)
The quality of being unbeatable, undefeatability.
Synonyms
*unbeatableness
*undefeatability
*undefeatableness (rare)
*invincibility
*invulnerability
*impregnability