Synonyms|713Antonyms|152|Broader|9Narrower|8Related|663
2
grave
2
gravid
2
great(dense, profuse)
2
grievous
2
grueling
2
hardened(adjective, set, strong, hard, tough)
2
imporous(closure, density)
2
incompressible(adjective, firm, dense, density)
2
indiscernible(adjective, incomprehensible)
2
insensible(adjective, hard, unfeeling, unsympathetic, hardened)
2
insoluble(adjective, unable, unintelligibility, answered)
2
invisible(obscure, dark, superior, mysterious, supernatural)
2
jam-packed(adjective, close, strong, solid, short)
2
jammed(packed, crowded, jam-packed)
2
lowering(dark, gloomy, dirty, dreary, misty)
2
misty(dark, gloomy, dense, cloudy, impervious)
2
monolithic
2
numinous(obscure, dark, superior, mysterious, supernatural)
2
obfuscated
2
obtuse(adjective, hard, unfeeling, unsympathetic, prepared)
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APASmart Define. (2015). impenetrable thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/impenetrable/thesaurus/synonyms
ChicagoSmart Define. 2015. "impenetrable thesaurus" https://smartdefine.org/impenetrable/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2015, impenetrable thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/impenetrable/thesaurus/synonyms>.
MLASmart Define. "impenetrable thesaurus" 10 April 2015. Web. 23 September 2026. <https://smartdefine.org/impenetrable/thesaurus/synonyms>