55 entries under stiff topic. ×

4
concrete(adjective, set, hard, tough, solid)
3
crowded(adjective, close, set, solid, heavy)
3
inflexible(adjective, set, strong, hard, tough)
3
rigid(adjective, set, strong, hard, tough)
3
strong(adjective, close, set, hard, secure)
2
callous(adjective, set, hard, firm)
2
compacted(adjective, set, strong, hard, firm)
2
concentrated(adjective, set, hard, tough, firm)
2
consolidated(adjective, close, set, firm, solid)
2
hardened(adjective, set, strong, hard, tough)
2
solidified(adjective, set, hard, tough, solid)
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
congealed(adjective, set, hard, tough, solid)
1
curdled(adjective, set, solid, heavy, deep)
1
fixed(adjective, set, solid, heavy, short)
1
gelatinous(adjective, set, solid, heavy, deep)
1
gloppy(adjective, set, solid, heavy, deep)
11 years ago|15k views|share |citing 
APASmart Define. (2015). impenetrable thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/impenetrable/thesaurus/synonyms
ChicagoSmart Define. 2015. "impenetrable thesaurus" https://smartdefine.org/impenetrable/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, impenetrable thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/impenetrable/thesaurus/synonyms>.
MLASmart Define. "impenetrable thesaurus" 10 April 2015. Web. 25 September 2026. <https://smartdefine.org/impenetrable/thesaurus/synonyms>