142 entries under substantial topic. ×

12
appreciable(adjective, large, considerable, noticed)
12
chief(adjective, superior, big, unusual, important)
11
essential(adjective, importance, big, important, original)
10
conspicuous(adjective, clear, solid, extraordinary, big)
9
decisive(adjective, great, extraordinary, big, important)
9
noticeable(adjective, clear, solid, extraordinary, unusual)
9
principal(adjective, good, great, big, important)
7
large(adjective, strong, big, important)
7
pressing(verb, adjective, tough, severe, big)
7
rich(adjective, strong, sound, intense, comfort)
7
substantive
6
distinguished(adjective, extraordinary, superior, big, unusual)
6
exceptional(adjective, solid, extraordinary, superior, big)
6
marked(adjective, clear, solid, extraordinary, superior)
6
necessary(adjective, big, important, original)
6
primary(adjective, superior, big, unusual, important)
6
respectable(adjective, large, admired, respected)
6
salient(adjective, extraordinary, unusual, important)
6
tidy(adjective, large, considerable)
6
urgent(adjective, clear, tough, severe, big)
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APASmart Define. (2016). significant thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/significant/thesaurus/synonyms
ChicagoSmart Define. 2016. "significant thesaurus" https://smartdefine.org/significant/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, significant thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/significant/thesaurus/synonyms>.
MLASmart Define. "significant thesaurus" 4 March 2016. Web. 23 September 2026. <https://smartdefine.org/significant/thesaurus/synonyms>