72 entries under adjective topic. ×

18
impenetrable(solid, dense, unaffected, unyielding)
12
insurmountable(do, unreasonable, useless, remote)
11
impervious(solid, unreasonable, useless, absurd)
10
inaccessible(unreasonable, useless, out, absurd)
8
dense(solid, resistant, impervious)
8
indomitable(steadfast, unyielding, insuperable)
7
impermeable(solid, dense, unaffected, unyielding)
7
insuperable(strong, secure, do, resolute)
7
unpassable
5
blocked(dark, inaccessible)
5
pathless(closure, closed)
5
thick(solid, dense)
4
invincible
4
unconquerable
3
closed(dark, inaccessible)
3
obscure(solid, dense)
3
obstructed(dark, closed, inaccessible)
3
unsurmountable
2
blockaded
2
compact(solid, dense)
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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>