127 entries under tough topic. ×

2
steely(adjective, strong, hard, severe)
2
stolid(adjective, rational, straightforward, sober)
2
strict(adjective, strong, hard, severe)
2
uphill(adjective, easy, rough, difficult)
1
onerous(adjective, hard, severe, rough)
1
apathetic(adjective, rational, straightforward, sober)
1
astringent(adjective, close, strong, hard)
1
authoritarian(adjective, strong, hard, severe)
1
bitter(adjective, strong, hard, severe)
1
bothersome(adjective, hard, rough, difficult)
1
by the book(expression, adjective, idiom, strong, hard)
1
cold(adjective, calm, close, hard)
1
cold-blooded(adjective, rational, straightforward, sober)
1
demanding(adjective, hard, difficult, harsh)
1
difficile(adjective, rough, difficult, heavy)
1
disciplinary(adjective, strong, hard, severe)
1
down-to-earth(adjective, calm, plain, restrained)
1
dry(adjective, rational, straightforward, temperate)
1
dyed-in-the-wool(adjective, strong, hard, severe)
1
earthy(adjective, rational, straightforward, sober)
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APASmart Define. (2016). serious thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 29, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 29 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>