918 entries under adjective topic. ×

93
grave(calm, dull, quiet, help)
50
severe(calm, help, bad, strong)
43
weighty(good, dull, hard, great)
39
solemn(calm, dull, quiet, cool)
37
important(good, great, severe, extraordinary)
37
earnest(noun, calm, dull, work)
32
critical(hard, great, tough, severe)
31
significant(good, great, extraordinary, importance)
31
sad(hard, difficult, complex, importance)
30
sober(calm, dull, quiet, cool)
30
difficult(hard, tough, easy, harsh)
29
grievous(help, hard, great, tough)
28
momentous(good, great, severe, extraordinary)
27
consequential(good, harsh, importance, big)
27
tough(bad, strong, hard, easy)
26
ambitious(hard, difficult, importance, complex)
26
hard(strong, tough, easy, severe)
26
profound(hard, difficult, complex, deep)
25
arduous(hard, tough, easy, difficult)
25
nasty(bad, hard, difficult, offensive)
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APASmart Define. (2016). serious thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 23 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>