Synonyms|713Antonyms|152|Broader|9Narrower|8Related|663
2
arduous
2
backbreaking
2
callous(adjective, set, hard, firm, stiff)
2
clayey
2
cloggy
2
close-knit(heavy, thick, packed, compressed, crowded)
2
closed to(expression, unaffected, unyielding, unbending, resistant)
2
clouded
2
compacted(adjective, set, strong, hard, firm)
2
concentrated(adjective, set, hard, tough, firm)
2
congested(adjective, close, solid, short, substantial)
2
consolidated(adjective, close, set, firm, solid)
2
crammed(dense, profuse, packed, crowded, jam-packed)
2
defensible
2
dumb
2
enceinte
2
equivocal
2
expectant
2
fathomless
2
formidable(adjective, invulnerable)
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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>