(n.) An atom which has a valence of seven, and which can be theoretically combined with, substituted for or replaced by, seven monad atoms or radicals; as, iodine is a heptad in iodic acid. Also used as an adjective.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). heptad. Retrieved September 20, 2026, from http://smartdefine.org/heptad/definitions/2016014 |
| Chicago | Webster's. 2011. "heptad" http://smartdefine.org/heptad/definitions/2016014 (accessed September 20, 2026). |
| Harvard | Webster's 2011, heptad, Smart Define, viewed 20 September, 2026, <http://smartdefine.org/heptad/definitions/2016014>. |
| MLA | Webster's. "heptad" 27 May 2011. Web. 20 September 2026. <http://smartdefine.org/heptad/definitions/2016014> |