- Definitions|2
- Thesaurus|1.5k
- Abbreviations|0
308 entries under adjective topic. ×
| firm(close, set, hard, solid) | |
| unintelligible(knowledge, obscure, solid, dark) | |
| invulnerable(unaffected, unyielding, safety, unbending) | |
| mysterious(obscure, solid, strange, secret) | |
| enigmatic(obscure, difficult, solid, strange) | |
| inviolable(dense, unfathomable, impervious) | |
| deep(set, obscure, solid, heavy) | |
| heavy(set, hard, tough, solid) | |
| impregnable(unyielding, safety) | |
| close(set, hard, tough, solid) | |
| inexplicable(obscure, solid, dark, strange) | |
| recondite | |
| inaccessible(hard, unfeeling, unsympathetic, prepared) | |
| invincible | |
| mystic(obscure, solid, dark, superior) | |
| occult(obscure, dark, superior, strange) | |
| tight(close, solid, short, substantial) | |
| condensed(set, hard, tough, solid) | |
| murky(obscure, solid, dark, gloomy) | |
| stony(hard, firm, stiff, unfeeling) |
For more, visit
Impenetrable on
Power Thesaurus
| APA | Smart Define. (2015). impenetrable thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/impenetrable/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "impenetrable thesaurus" https://smartdefine.org/impenetrable/thesaurus/synonyms (accessed September 25, 2026). |
| Harvard | Smart Define 2015, impenetrable thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/impenetrable/thesaurus/synonyms>. |
| MLA | Smart Define. "impenetrable thesaurus" 10 April 2015. Web. 25 September 2026. <https://smartdefine.org/impenetrable/thesaurus/synonyms> |