115 entries under heavy topic. ×

93
grave(adjective, calm, dull, quiet, help)
50
severe(adjective, calm, help, bad, strong)
43
weighty(adjective, good, dull, hard, great)
39
solemn(adjective, calm, dull, quiet, cool)
37
important(adjective, good, great, severe, extraordinary)
37
earnest(noun, adjective, calm, dull, work)
32
critical(adjective, hard, great, tough, severe)
31
significant(adjective, good, great, extraordinary, importance)
30
sober(adjective, calm, dull, quiet, cool)
29
grievous(adjective, help, hard, great, tough)
28
momentous(adjective, good, great, severe, extraordinary)
27
consequential(adjective, good, harsh, importance, big)
23
sedate(adjective, calm, dull, cool, severe)
22
staid(adjective, calm, dull, set, cool)
19
burdensome(adjective, hard, difficult, big)
19
vital(adjective, great, severe, importance, big)
17
substantial(adjective, importance, big, important)
16
pressing(adjective, hard, tough, difficult, big)
15
crucial(adjective, great, severe, extraordinary, big)
15
meaningful(adjective, good, great, severe, extraordinary)
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APASmart Define. (2016). serious thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 25 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>