100 entries under solid topic. ×

12
sound(adjective, calm, good, strong, secure)
7
reliable(adjective, calm, good, strong, secure)
6
secure(adjective, calm, good, strong, sound)
6
stable(adjective, strong, sound, secure, tough)
6
substantial(adjective, calm, good, strong, sound)
5
set(adjective, calm, strong, steady)
5
steady(adjective, calm, strong, sound, secure)
5
sturdy(adjective, calm, strong, sound, secure)
5
sure(adjective, calm, strong, reasonable, sensible)
4
balanced(adjective, calm, strong, secure, easy)
4
deep-rooted(adjective, calm, strong, steady)
4
durable(adjective, calm, strong, sound, secure)
4
fast(adjective, calm, strong, secure)
4
stout(adjective, calm, strong, sound, secure)
3
certain(adjective, strong, reasonable, easy, sensible)
3
enduring(adjective, calm, strong, sound, secure)
3
lasting(calm, strong, steady, substantial)
3
powerful(adjective, good, strong, great, sound)
3
safe(calm, strong, secure, steady)
3
settled(adjective, strong, secure, easy)
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APASmart Define. (2016). well-founded thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/well-founded/thesaurus/synonyms
ChicagoSmart Define. 2016. "well-founded thesaurus" https://smartdefine.org/well-founded/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, well-founded thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/well-founded/thesaurus/synonyms>.
MLASmart Define. "well-founded thesaurus" 29 March 2016. Web. 23 September 2026. <https://smartdefine.org/well-founded/thesaurus/synonyms>