7
decisive(adjective, great, severe, firm, extraordinary)
7
dedicated(adjective, complete, warm, total, passionate)
7
detrimental(adjective, importance, main, dangerous, extremely significant)
7
devoted(adjective, complete, warm, total, passionate)
7
donnish(adjective, importance, valuable, main, notable)
7
exciting(adjective, importance, valuable, main, notable)
7
far reaching(adjective, importance, valuable, main, notable)
7
genuine(adjective, set, open, honest, total)
7
haughty(adjective, importance, valuable, main, notable)
7
high(adjective, important, prominent, exalted)
7
high-up(adjective, importance, valuable, main, notable)
7
key-note(adjective, importance, valuable, main, notable)
7
not good
7
perilous(adjective, bad, heavy, uncertain, significant)
7
precious(adjective, importance, main, greatness, extremely significant)
7
red hot(adjective, importance, main, extremely significant)
7
relevant(adjective, importance, big, significant, substantial)
7
significative(adjective, importance, valuable, main, notable)
6
ardent(adjective, complete, keen, warm, total)
6
big league(adjective, importance, important, main, extremely significant)
10 years ago|45k views|share |citing 
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>