3
unsurmountable(adjective, impossibility)
2
blockaded(adjective, closed)
2
compact(adjective, solid, dense)
2
forbidden(adjective, closed)
2
imperviable(unaffected, unyielding, unbending, resistant, unreceptive)
2
impossible(adjective, unreasonable, useless, absurd, hopeless)
2
impracticable
2
incomprehensible(adjective, solid, dense)
2
invulnerable(adjective, strong, resolute, unaffected, unyielding)
2
murky(adjective, solid, dense)
2
mysterious(adjective, solid, dense)
2
sealed(adjective, unaffected, unyielding, unbending, resistant)
2
tight(unaffected, unyielding, unbending, resistant, unreceptive)
2
unattainable(adjective, inaccessible, impossible, impossibility)
2
untrodden(adjective, closure, closed)
1
blind(adjective, hidden, covered)
1
bulletproof(adjective, solid, dense, untouchable, invincible)
1
compressed
1
death
1
desperate
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APASmart Define. (2015). impassable thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/impassable/thesaurus/synonyms
ChicagoSmart Define. 2015. "impassable thesaurus" https://smartdefine.org/impassable/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, impassable thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/impassable/thesaurus/synonyms>.
MLASmart Define. "impassable thesaurus" 14 April 2015. Web. 21 September 2026. <https://smartdefine.org/impassable/thesaurus/synonyms>