93 entries under difficult topic. ×

19
sensitive(adjective, hard, complex)
19
sophisticated(adjective, hard, complex)
19
sticky(adjective, hard, complex, awkward)
19
toilful(adjective, hard, complex, awkward)
19
toilsome(adjective, hard, harsh, cruel)
18
hefty(adjective, hard, complex)
18
messy(adjective, hard, unpleasant, complex)
18
taxing(adjective, hard, complex)
18
tricky(adjective, hard, complex, awkward)
18
trying(adjective, hard, complex)
18
unbearable(adjective, hard, complex)
16
pressing(adjective, hard, tough, big)
14
urgent(adjective, hard, tough, severe)
10
terrible(adjective, bad, great, extraordinary)
8
challenging(adjective, hard, tough, importance)
6
formidable(adjective, bad, hard, unpleasant)
5
distressing(adjective, tough, severe, rough)
5
strenuous(adjective, hard, severe, rough)
4
violent(adjective, hard, severe, rough)
2
awkward(adjective, demanding, grueling, problematical)
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APASmart Define. (2016). serious thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 22 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>