308 entries under adjective topic. ×

2
overweight
2
sealed(fast, short, unaffected, unyielding)
2
secret(obscure, dark, superior, strange)
2
secure
2
smoky(dark, gloomy, dirty, dreary)
2
solidified(set, hard, tough, solid)
2
sonorous
2
stiff(set, hard, tough, firm)
2
supernatural(obscure, dark, mysterious, spiritual)
2
unseen(hidden, latency implication)
2
unsusceptible(hard, unfeeling, unsympathetic, hardened)
2
watertight(fast, short, unaffected, unyielding)
1
Delphic
1
accustomed(hard, unfeeling, unsympathetic, prepared)
1
benumbed(hard, unfeeling, unsympathetic, prepared)
1
blurred
1
bulletproof
1
caked(set, solid, heavy, deep)
1
case-hardened(hard, unfeeling, unsympathetic, prepared)
1
clabbered(set, solid, heavy, deep)
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APASmart Define. (2015). impenetrable thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/impenetrable/thesaurus/synonyms
ChicagoSmart Define. 2015. "impenetrable thesaurus" https://smartdefine.org/impenetrable/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, impenetrable thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/impenetrable/thesaurus/synonyms>.
MLASmart Define. "impenetrable thesaurus" 10 April 2015. Web. 26 September 2026. <https://smartdefine.org/impenetrable/thesaurus/synonyms>