- Definitions|2
- Thesaurus|1.8k
- Abbreviations|0
140 entries under hard topic. ×
| burdensome(adjective, severe, rough, difficult) | |
| onerous(adjective, severe, rough, difficult) | |
| unrelenting(adjective, strong, tough, severe) | |
| immovable(adjective, set, strong, tough) | |
| unchangeable(adjective, resolute, rigid, inflexible) | |
| unsparing(adjective, strong, tough, severe) | |
| adamantine(adjective, set, strong, tough) | |
| exhausting(adjective, tough, severe, rough) | |
| flinty(adjective, strong, tough, severe) | |
| immutable(adjective, resolute, rigid, inflexible) | |
| intemperate(adjective, tough, severe, rough) | |
| resolute(adjective, intense, rigid, inflexible) | |
| steely(adjective, set, strong, tough) | |
| strenuous(adjective, tough, severe, rough) | |
| strong(adjective, tough, severe, sturdy) | |
| stubborn(adjective, strong, tough, severe) | |
| authoritarian(adjective, strong, tough, severe) | |
| fierce(adjective, tough, harsh, intense) | |
| fixed(adjective, severe, stiff, rigid) | |
| formidable(adjective, tough, severe, rough) |
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| APA | Smart Define. (2016). rigorous thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/rigorous/thesaurus/synonyms |
| Chicago | Smart Define. 2016. "rigorous thesaurus" https://smartdefine.org/rigorous/thesaurus/synonyms (accessed September 23, 2026). |
| Harvard | Smart Define 2016, rigorous thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/rigorous/thesaurus/synonyms>. |
| MLA | Smart Define. "rigorous thesaurus" 26 February 2016. Web. 23 September 2026. <https://smartdefine.org/rigorous/thesaurus/synonyms> |