heptad Meaning, Definition & Usage

  1. noun the cardinal number that is the sum of six and one
    seven; sevener; VII; septet; 7; septenary.

WordNet

Hep"tad noun
Etymology
L. heptas the number seven. Gr. , , fr. "epta` seven.
Definitions
  1. (Chem.) 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 1913