116 entries under substantial topic. ×

2
resolute(adjective, calm, strong, secure, easy)
2
sinewy(adjective, strong, tough, fit, solid)
2
tenacious(adjective, strong, secure, tough, fit)
2
thick(adjective, strong, hard, compact)
2
unwavering(adjective, calm, strong, secure, firm)
1
abiding(adjective, calm, strong, secure, tough)
1
bolted(strong, secure, fast, short)
1
brick-wall(adjective, calm, strong, secure, firm)
1
calm(adjective, strong, secure, reasonable, firm)
1
capable(adjective, strong, direct, tough, fit)
1
close(adjective, strong, hard, firm, true)
1
closed(strong, secure, stable, unmoving)
1
compacted(adjective, strong, hard, sturdy)
1
consolidated(adjective, strong, hard, complete, total)
1
deep-rooted(adjective, calm, strong, solid, steady)
1
dimensional(adjective, strong, hard, sturdy)
1
equable(adjective, calm, strong, secure, firm)
1
fixed resistant(expression, calm, strong, solid)
1
hard as nails(expression, adjective, idiom, strong, tough)
1
heavy-duty(adjective, strong, tough, solid, heavy)
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APASmart Define. (2016). sound thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/sound/thesaurus/synonyms
ChicagoSmart Define. 2016. "sound thesaurus" https://smartdefine.org/sound/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2016, sound thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/sound/thesaurus/synonyms>.
MLASmart Define. "sound thesaurus" 24 March 2016. Web. 26 September 2026. <https://smartdefine.org/sound/thesaurus/synonyms>