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

But this oddness belongs to other numbers also (pentad, heptad, &c.).

From Project Gutenberg

Heptad, a term in chemistry to denote an atom that is the equivalent of seven atoms of hydrogen, from hepta, seven.

From Project Gutenberg