noun
- The cardinal number that is the sum of twenty and one.
- synonyms: twenty-one, XXI
adjective
- Being one more than twenty.
- synonyms: twenty-one, xxi
WordNet 3.0 © 2006 by Princeton University
| APA | WordNet. (2010). 21. Retrieved September 20, 2026, from http://smartdefine.org/21/definitions/1166870 |
| Chicago | WordNet. 2010. "21" http://smartdefine.org/21/definitions/1166870 (accessed September 20, 2026). |
| Harvard | WordNet 2010, 21, Smart Define, viewed 20 September, 2026, <http://smartdefine.org/21/definitions/1166870>. |
| MLA | WordNet. "21" 23 October 2010. Web. 20 September 2026. <http://smartdefine.org/21/definitions/1166870> |