| APA | Smart Define. (2015). toughness thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/toughness/thesaurus/antonyms |
| Chicago | Smart Define. 2015. "toughness thesaurus" https://smartdefine.org/toughness/thesaurus/antonyms (accessed September 28, 2026). |
| Harvard | Smart Define 2015, toughness thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/toughness/thesaurus/antonyms>. |
| MLA | Smart Define. "toughness thesaurus" 21 December 2015. Web. 28 September 2026. <https://smartdefine.org/toughness/thesaurus/antonyms> |