118 entries under significant topic. ×

2
eventful(great, extraordinary, unusual, important)
2
exalted(adjective, important, critical, prominent)
2
extensive(big, substantial, large, valuable)
2
extraordinary(adjective, great, unusual, important, famous)
2
hazardous(adjective, bad, severe, heavy)
2
large(big, substantial, valuable, vital)
2
necessary(adjective, big, important, substantial)
2
primary(big, important, substantial, valuable)
2
principal(great, big, important, substantial)
2
salient(adjective, big, important, substantial)
2
signal(great, extraordinary, important, outstanding)
2
solid(adjective, strong, big, pure, important)
1
chief(adjective, great, big, heavy, important)
1
conspicuous(adjective, great, unusual, important, famous)
1
determining(big, important, substantial, valuable)
1
enduring(adjective, great, complete, warm, total)
1
esteemed(grand, vital, imperative, respected)
1
exceptional(adjective, great, big, unusual, heavy)
1
exigent(adjective, hard, tough, difficult, big)
1
far-reaching(adjective, big, important, substantial)
10 years ago|45k views|share |citing 
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>