135 entries under adjective topic. ×

47
strong(sound, reasonable, strain, rational)
41
firm(strain, true, firmness, constant)
40
hard(strain, firmness, labour, hardiness)
37
sound(reasonable, strain, firm, true)
37
stable(strain, firm, true, firmness)
35
stiff(strain, firmness, labour, hardiness)
22
fast(strain, firm, firmness, constant)
22
tenable(strain, firmness, labour, safety)
22
unyielding(strain, firmness, labour, hardiness)
20
proof(strain, firmness, labour, hardiness)
20
resistant(strain, firmness, labour, hardiness)
20
steadfast(strain, firmness, labour, hardiness)
19
rigid(strain, firmness, labour, hardiness)
19
robust(strain, firmness, labour, hardiness)
19
substantial(strain, firmness, labour, hardiness)
19
tight(strain, firm, true, firmness)
18
constant(strain, firmness, labour, hardiness)
18
durable(strain, firmness, labour, hardiness)
18
immune(strain, firmness, safe, labour)
18
lasting(strain, firmness, labour, hardiness)
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APASmart Define. (2015). impregnable thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/impregnable/thesaurus/synonyms
ChicagoSmart Define. 2015. "impregnable thesaurus" https://smartdefine.org/impregnable/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, impregnable thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/impregnable/thesaurus/synonyms>.
MLASmart Define. "impregnable thesaurus" 10 April 2015. Web. 21 September 2026. <https://smartdefine.org/impregnable/thesaurus/synonyms>