- Definitions|1
- Thesaurus|748
- Abbreviations|0
| constant | |
| dense(adjective, strong, hard, firm, solid) | |
| difficult | |
| fibrous(adjective, strong, hard, solid, stiff) | |
| fit(adjective, strong, hard, solid, stiff) | |
| fortified | |
| galvanized | |
| hard-bitten(adjective, strong, hard, solid, stiff) | |
| hard as nails(expression, adjective, idiom, strong, hard) | |
| hardened(adjective, strong, hard, firm, solid) | |
| hardy(adjective, strong, hard, solid, stiff) | |
| healthy(adjective, strong, hard, solid, stiff) | |
| heavily clad | |
| heavy-duty | |
| immortal | |
| immutable | |
| indelible | |
| indigestible(adjective, strong, hard, solid, stiff) | |
| indurate(adjective, firm, stiff, rigid) | |
| indurated(adjective, firm, stiff, rigid) |
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| APA | Smart Define. (2016). unbreakable thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/unbreakable/thesaurus/synonyms |
| Chicago | Smart Define. 2016. "unbreakable thesaurus" https://smartdefine.org/unbreakable/thesaurus/synonyms (accessed September 25, 2026). |
| Harvard | Smart Define 2016, unbreakable thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/unbreakable/thesaurus/synonyms>. |
| MLA | Smart Define. "unbreakable thesaurus" 5 January 2016. Web. 25 September 2026. <https://smartdefine.org/unbreakable/thesaurus/synonyms> |