115 entries under heavy topic. ×

1
slavish(adjective, tough, rough, difficult)
1
strictly business(expression, adjective, great, weighty)
1
tiring(adjective, tough, severe, rough, difficult)
1
troublesome(adjective, hard, tough, severe, rough)
1
underlined(adjective, big, unusual, important)
1
uphill battle(expression, adjective, tough, rough, difficult)
1
vexatious(adjective, hard, severe, rough, difficult)
1
wearing(adjective, hard, tough, rough, difficult)
1
wearisome(adjective, hard, tough, severe, rough)
1
wearying(adjective, tough, rough, difficult)
1
wise(adjective, reasonable, keen, deep)
0
afflictive(adjective, severe, acute, dangerous)
0
big deal(expression, big, substantial)
0
blue-chip
0
bulky(big, significant, substantial, large)
0
cumbersome(severe, harsh, big, substantial)
0
cumbrous(big, substantial)
0
dense(adjective, strong, hard, tough, big)
0
fat(adjective, big, substantial, bulky)
0
feller(adjective, resolute, acute, destructive)
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APASmart Define. (2016). serious thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 27 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>