- (n.) The number four; a collection of four things; a quaternion.
- (n.) A tetravalent or quadrivalent atom or radical; as, carbon is a tetrad.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). tetrad. Retrieved September 23, 2026, from http://smartdefine.org/tetrad/definitions/2071546 |
| Chicago | Webster's. 2011. "tetrad" http://smartdefine.org/tetrad/definitions/2071546 (accessed September 23, 2026). |
| Harvard | Webster's 2011, tetrad, Smart Define, viewed 23 September, 2026, <http://smartdefine.org/tetrad/definitions/2071546>. |
| MLA | Webster's. "tetrad" 28 May 2011. Web. 23 September 2026. <http://smartdefine.org/tetrad/definitions/2071546> |