102 entries under difficult topic. ×

6
merciless(adjective, tough, rough, heavy)
6
operose(adjective, tough, severe, difficulty)
6
overpowering(adjective, tiring)
6
rigorous(adjective, hard, severe, rough)
6
rough(adjective, hard, great, tough, severe)
6
serious(adjective, hard, tough, severe, rough)
6
tedious(adjective, dull, boring, demanding)
6
time-consuming(adjective, hard, tough, slow)
6
tiresome(adjective, hard, severe, heavy)
6
wearing(adjective, dull, hard, tough)
5
complicated(adjective, hard, tough, severe, rough)
5
galling(adjective, tough, severe, heavy)
5
grueling(adjective, hard, tough, heavy)
5
intolerable(adjective, tiring)
4
complex
4
excessive(adjective, tiring)
4
ticklish
4
tricky(adjective, awkward, demanding, irritating)
3
cantankerous
3
finicky(adjective, tough, harsh, rigid)
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APASmart Define. (2015). onerous thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/onerous/thesaurus/synonyms
ChicagoSmart Define. 2015. "onerous thesaurus" https://smartdefine.org/onerous/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, onerous thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/onerous/thesaurus/synonyms>.
MLASmart Define. "onerous thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/onerous/thesaurus/synonyms>