93 entries under difficult topic. ×

20
involved(adjective, hard, complex, awkward)
20
massive(adjective, hard, complex)
20
oppressive(adjective, hard, complex)
20
sore(adjective, hard, complex)
20
stubborn(adjective, strong, hard, tough, firm)
20
troubled(adjective, hard, unhappy, gloomy)
19
backbreaking(adjective, hard, complex, awkward)
19
burdensome(adjective, hard, big, heavy)
19
complicated(adjective, hard, complex, awkward)
19
cruel(adjective, strong, hard, tough, severe)
19
disturbing(adjective, hard, complex)
19
esoteric(adjective, hard, complex)
19
grinding(adjective, hard, harsh, cruel)
19
hard-nosed(adjective, strong, hard, tough, severe)
19
heavy(adjective, strong, hard, great, tough)
19
intricate(adjective, hard, complex, awkward)
19
knotty(adjective, hard, complex, awkward)
19
ponderous(adjective, hard, complex)
19
rough(adjective, bad, strong, hard, tough)
19
rugged(adjective, strong, hard, tough)
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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>