75 entries under dense topic. ×

22
impenetrable(adjective, set, hard, tough, solid)
13
impassable(adjective, solid, unreasonable, useless, absurd)
12
tight(adjective, proof, unyielding, unbending)
11
hermetic(adjective, solid, fast, short)
6
compact(adjective, set, hard, tough, solid)
5
firm(adjective, set, strong, hard, tough)
4
hard(adjective, set, tough, firm, solid)
4
inviolable(adjective, secure, solid, safe)
3
thick(adjective, hard, solid, rigid)
2
close(adjective, set, hard, tough, solid)
2
stiff(adjective, set, hard, tough, solid)
1
abundant(profuse, impenetrable)
1
caked(adjective, set, solid, heavy, deep)
1
clabbered(adjective, set, solid, heavy, deep)
1
clotted(adjective, set, solid, heavy, deep)
1
coagulated(adjective, set, solid, heavy, deep)
1
compressed(adjective, set, hard, tough, solid)
1
concentrated(adjective, set, hard, tough, solid)
1
concrete(adjective, set, hard, tough, solid)
1
condensed(adjective, set, hard, tough, solid)
11 years ago|11k views|share |citing 
APASmart Define. (2015). impervious thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/impervious/thesaurus/synonyms
ChicagoSmart Define. 2015. "impervious thesaurus" https://smartdefine.org/impervious/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, impervious thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/impervious/thesaurus/synonyms>.
MLASmart Define. "impervious thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/impervious/thesaurus/synonyms>