Heptad is a see also of polyad.
As nouns the difference between heptad and polyad
is that heptad is a group of seven things while polyad is a group consisting of an indeterminate number of things or people.
polyad
English
See also
* monad
* dyad
* triad
* tetrad
* pentad
* hexad
* heptad
* octad
* nonad
* decad
* See also