- (a.) Consisting of four; by fours or in sets of four.
- (n.) The number four.
- (a.) Later than or subsequent to, the Tertiary; Post-tertiary; as, the Quaternary age or Age of man.
- (n.) The Quaternary age, era or formation. See the Chart of Geology.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). quaternary. Retrieved September 24, 2026, from http://smartdefine.org/quaternary/definitions/2051768 |
| Chicago | Webster's. 2011. "quaternary" http://smartdefine.org/quaternary/definitions/2051768 (accessed September 24, 2026). |
| Harvard | Webster's 2011, quaternary, Smart Define, viewed 24 September, 2026, <http://smartdefine.org/quaternary/definitions/2051768>. |
| MLA | Webster's. "quaternary" 27 May 2011. Web. 24 September 2026. <http://smartdefine.org/quaternary/definitions/2051768> |