127 entries under tough topic. ×
| herculean(adjective, rough, difficult, heavy) | |
| immovable(adjective, strong, hard, sturdy) | |
| insensible(adjective, strong, hard, sturdy) | |
| robust(adjective, strong, hard, sturdy) | |
| steel(adjective, strong, hard, sturdy) | |
| thick(adjective, strong, hard, sturdy) | |
| tough inflexible(expression, strong, hard, sturdy) |
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| APA | Smart Define. (2016). serious thesaurus. Retrieved September 30, 2026, from https://smartdefine.org/serious/thesaurus/synonyms |
| Chicago | Smart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 30, 2026). |
| Harvard | Smart Define 2016, serious thesaurus, Smart Define, viewed 30 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>. |
| MLA | Smart Define. "serious thesaurus" 24 February 2016. Web. 30 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms> |