79 entries under hard topic. ×

1
thickened(adjective, firm, solid, tense)
1
unflexible(adjective, firm, solid, tense)
1
ungraceful(adjective, firm, solid, tense)
1
unsupple(adjective, firm, solid, tense)
1
vicious(adjective, severe, rough, harsh)
1
wooden(adjective, firm, solid, tense)
0
close(tough, solid, rigid, inflexible)
0
close-grained(tough, solid, rigid, inflexible)
0
compact(solid, rigid)
0
compressed(tough, solid, rigid, inflexible)
0
concentrated(tough, solid, rigid, inflexible)
0
condensed(tough, solid, rigid, inflexible)
0
dense(solid, rigid)
0
fine-grained(tough, solid, rigid, inflexible)
0
impenetrable(solid, rigid)
0
impermeable(solid, rigid)
0
narrow(adjective, severe, rough, harsh)
0
nonporous(tough, solid, rigid, inflexible)
0
terrible(adjective, severe, rough, harsh)
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APASmart Define. (2015). refractory thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/refractory/thesaurus/synonyms
ChicagoSmart Define. 2015. "refractory thesaurus" https://smartdefine.org/refractory/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2015, refractory thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/refractory/thesaurus/synonyms>.
MLASmart Define. "refractory thesaurus" 10 April 2015. Web. 24 September 2026. <https://smartdefine.org/refractory/thesaurus/synonyms>