918 entries under adjective topic. ×

6
deliberate(calm, set, cool, severe)
6
demure(calm, cool, modest, shy)
6
formidable(bad, hard, difficult, unpleasant)
6
heartfelt(open, keen, warm, honest)
6
hearty(complete, keen, warm, total)
6
integral(importance, main, extremely significant)
6
life-threatening
6
menacing(bad, nasty, unpleasant, heavy)
6
noble(importance, important, significant, grand)
6
pivotal
6
reflective(set, deep, thoughtful, sober)
6
resolved(severe, firm, harsh, cruel)
6
threatening(bad, severe, unpleasant, heavy)
6
ugly(bad, nasty, offensive, unpleasant)
6
wholehearted(open, keen, warm, honest)
6
zealous(keen, warm, total, intense)
5
calm(cool, tough, sensible, relaxed)
5
devout(open, keen, warm, honest)
5
distressing(tough, severe, rough, difficult)
5
funereal(dull, dark, gloomy, sober)
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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>