9
impregnable(adjective, safety)
6
unassailable(adjective, safety)
6
unconquerable(adjective, insurmountable)
5
invincible
4
impenetrable(adjective, safety)
3
insuperable
3
inviolable
2
invulnerable
2
strong
2
unattackable
1
deathless
1
defensible
1
hard
1
immortal
1
imperishable
1
incontestable
1
incorruptible
1
indelible
1
indestructible
1
indomitable
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APASmart Define. (2015). inexpugnable thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/inexpugnable/thesaurus/synonyms
ChicagoSmart Define. 2015. "inexpugnable thesaurus" https://smartdefine.org/inexpugnable/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, inexpugnable thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/inexpugnable/thesaurus/synonyms>.
MLASmart Define. "inexpugnable thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/inexpugnable/thesaurus/synonyms>