- Definitions|2
- Thesaurus|716
- Abbreviations|0
135 entries under adjective topic. ×
| permanent(strain, firmness, labour, hardiness) | |
| steady(strain, firmness, safe, labour) | |
| viable(strain, firmness, labour, hardiness) | |
| impenetrable(unyielding, safety) | |
| secure(sound, reasonable, firm, true) | |
| unassailable(strong, secure, resolute, safe) | |
| invincible(strength, do, win, unyielding) | |
| invulnerable(strong, secure, resolute, safe) | |
| inviolable(secure, safe, snug, intact) | |
| unconquerable(strength, do, win, insurmountable) | |
| indomitable(strength, do, win, steadfast) | |
| inexpugnable | |
| safe(secure, harm, unquestionable, snug) | |
| insuperable | |
| unattackable | |
| indestructible | |
| protected(secure, safe, snug, intact) | |
| solid(safe, unyielding, sheltered, protected) | |
| unbeatable | |
| defendable(sound, reasonable, rational) |
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| APA | Smart Define. (2015). impregnable thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/impregnable/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "impregnable thesaurus" https://smartdefine.org/impregnable/thesaurus/synonyms (accessed September 22, 2026). |
| Harvard | Smart Define 2015, impregnable thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/impregnable/thesaurus/synonyms>. |
| MLA | Smart Define. "impregnable thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/impregnable/thesaurus/synonyms> |