heptad

American  

[hep-tad] / ˈhɛp tæd /

noun

1. the number seven.

2. a group of seven.

3. Chemistry. an element, atom, or group having a valence of seven.

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heptad British  

/ ˈhɛptæd /

noun

1. a group or series of seven

2. the number or sum of seven

3. an atom or element with a valency of seven

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Etymology

Origin of heptad

First recorded in 1650–60, heptad is from the Greek word heptad- (stem of heptás ). See hepta-, -ad ¹

Example Sentences

Seven, or the heptad, is a number very powerful for good or for evil.

From Curious Myths of the Middle Ages by Baring-Gould, S. (Sabine)

Indeed, the heptad of things finite is in all cases reducible to the pentad.

From Specimens of the Table Talk of Samuel Taylor Coleridge by Coleridge, Henry Nelson

Later on every idea will be a heptad, made up of seven elements.

From An Introduction to Yoga by Besant, Annie Wood

Thus one of the Meta molecules of iron, containing seven atoms, is identical in appearance with a Hyper heptad, but the latter dissociates into seven atoms, the former into two triads and a single atom.

From Occult Chemistry Clairvoyant Observations on the Chemical Elements by Sinnett, A. P.

The word pentad at once recalls to you the way in which the chemist speaks of a monad, triad, heptad, when he deals with elements.

From An Introduction to Yoga by Besant, Annie Wood