a group or series of seven the number or sum of seven an atom or element with a valency of seven
WordReference Random House Unabridged Dictionary of American English © 2025
hep•tad
(hep′tad),USA pronunciation n.
- Mathematicsthe number seven.
- Mathematicsa group of seven.
- Chemistryan element, atom, or group having a valence of seven.
- Greek heptad- (stem of heptás). See hepta-, -ad1
- 1650–60
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