heptad

[hep-tad]

noun

1. the number seven.

2. a group of seven.

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

heptad

/ 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

Word History and Origins

Origin of heptad¹

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

Word History and Origins

Origin of heptad¹

C17: from Greek heptas seven

Example Sentences

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

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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.

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

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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.

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Colours may best be expressed by a heptad, the largest possible formula for things finite, as the pentad is the smallest possible form.

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