127 entries under tough topic. ×

1
tiring(adjective, severe, rough, difficult)
1
troublesome(adjective, hard, severe, rough)
1
unaffected(adjective, open, honest, true)
1
unembellished(adjective, rational, straightforward, sober)
1
unidealistic(adjective, rational, straightforward, sober)
1
unimaginative(adjective, rational, straightforward, sober)
1
unimpassioned(adjective, calm, dark, restrained)
1
unrelenting(adjective, close, strong, hard)
1
unsentimental(adjective, rational, straightforward, sober)
1
unsparing(adjective, close, strong, hard)
1
unvarnished(adjective, rational, straightforward, sober)
1
uphill battle(expression, adjective, rough, difficult)
1
wearing(adjective, hard, rough, difficult)
1
wearisome(adjective, hard, severe, rough)
1
wearying(adjective, rough, difficult, heavy)
0
adamant(adjective, strong, hard, firm)
0
adamantine(adjective, strong, hard, sturdy)
0
dense(adjective, strong, hard, big)
0
ferric(adjective, strong, hard, sturdy)
0
ferrous(adjective, strong, hard, sturdy)
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APASmart Define. (2016). serious thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 30, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 30 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>