2
rough(adjective, severity, sophistication, harshness, grievousness)
2
solemn(expression, adjective, severity, earnest, harshness)
2
stern(adjective, hard, severe, harsh)
2
tough(adjective, severity, sophistication, harshness, grievousness)
1
sincere(adjective, false, sober, disciplined, insincere)
1
arduous(adjective, severity, sophistication, harshness, grievousness)
1
complicated(adjective, severity, sophistication, harshness, grievousness)
1
difficult(adjective, severity, sophistication, harshness, grievousness)
1
hardboiled(adjective, upset, light, sober, disciplined)
1
harsh(adjective, hard, severe, stern)
1
involved(adjective, importance, significance, consequence, eminence)
1
laborious(adjective, severity, sophistication, harshness, grievousness)
1
momentous(adjective, importance, significance, consequence, eminence)
1
operose(adjective, severity, sophistication, harshness, grievousness)
1
somber(adjective, light, bright, sober, disciplined)
1
strict(adjective, hard, severe, harsh, stern)
1
unexcited(adjective, light, happy, sober, disciplined)
0
businesslike
-2
grim(adjective, severity, sophistication, harshness, grievousness)
-2
heavyweight(adjective, severity, sophistication, harshness, grievousness)
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APASmart Define. (2015). unserious thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/unserious/thesaurus/antonyms
ChicagoSmart Define. 2015. "unserious thesaurus" https://smartdefine.org/unserious/thesaurus/antonyms (accessed September 29, 2026).
HarvardSmart Define 2015, unserious thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/unserious/thesaurus/antonyms>.
MLASmart Define. "unserious thesaurus" 10 April 2015. Web. 29 September 2026. <https://smartdefine.org/unserious/thesaurus/antonyms>