118 entries under significant topic. ×

1
foremost(basic, prime, vital, earnest)
1
front-page(great, big, heavy, substantial)
1
generous(adjective, strong, solid, big, important)
1
hairy(adjective, bad, rough, difficult, heavy)
1
imperative(adjective, big, important, substantial)
1
leading(adjective, good, important, powerful)
1
marked(big, unusual, substantial, valuable)
1
memorable(adjective, great, unusual, important, famous)
1
mind-blowing(adjective, great, unusual, important, exceptional)
1
observable(adjective, great, extraordinary, unusual, important)
1
of moment(expression, big, substantial, valuable)
1
of note(expression, big, substantial, valuable)
1
of substance(expression, big, substantial, valuable)
1
paramount(important, critical, basic, prime)
1
playing hard ball(expression, adjective, idiom, great, heavy)
1
red-letter(adjective, great, extraordinary, unusual, important)
1
something(big, outstanding, substantial, valuable)
1
stable(adjective, strong, solid, big, important)
1
standout(great, extraordinary, big, substantial)
1
sturdy(adjective, strong, hard, tough, solid)
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APASmart Define. (2016). serious thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 26 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>