| APA | Smart Define. (2016). playfulness thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/playfulness/thesaurus/antonyms |
| Chicago | Smart Define. 2016. "playfulness thesaurus" https://smartdefine.org/playfulness/thesaurus/antonyms (accessed September 29, 2026). |
| Harvard | Smart Define 2016, playfulness thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/playfulness/thesaurus/antonyms>. |
| MLA | Smart Define. "playfulness thesaurus" 25 January 2016. Web. 29 September 2026. <https://smartdefine.org/playfulness/thesaurus/antonyms> |