58 entries under heavy topic. ×

3
painful(adjective, hard, tough, severe, difficult)
3
taxing
3
toilsome(adjective, hard, tough, severe, rough)
3
trying
3
uphill(adjective, hard, tough, severe, rough)
2
difficile(adjective, tough, rough, difficult)
2
excessive(adjective, severe, difficult, harsh)
2
grinding(adjective, tough, severe, rough, difficult)
2
hairy(adjective, tough, severe, rough, difficult)
2
intolerable(adjective, tough, severe, harsh)
2
knotty(adjective, tough, severe, rough, difficult)
2
operose(adjective, hard, tough, severe, rough)
2
troublesome(adjective, hard, tough, severe, rough)
2
weighty
1
backbreaking(adjective, hard, tough, severe, rough)
1
complicated(adjective, tough, rough, difficult)
1
distressing(adjective, tough, severe, rough, difficult)
1
fatiguing(adjective, hard, tough, severe, rough)
1
grueling(adjective, hard, tough, severe, difficult)
1
involved(adjective, tough, rough, difficult)
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APASmart Define. (2016). rigorous thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/rigorous/thesaurus/synonyms
ChicagoSmart Define. 2016. "rigorous thesaurus" https://smartdefine.org/rigorous/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, rigorous thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/rigorous/thesaurus/synonyms>.
MLASmart Define. "rigorous thesaurus" 26 February 2016. Web. 23 September 2026. <https://smartdefine.org/rigorous/thesaurus/synonyms>