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A group or series of seven.

[Greek heptas, heptad-, the number seven, from hepta, seven; see septm̥ in Indo-European roots.]


1. (Mathematics) a group or series of seven
2. (Mathematics) the number or sum of seven
3. (Chemistry) an atom or element with a valency of seven
[C17: from Greek heptas seven]


(ˈhɛp tæd)

1. the number seven.
2. a group of seven.
[1650–60; < Greek heptad-, s. of heptás. See hepta-, -ad1]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.heptad - the cardinal number that is the sum of six and oneheptad - the cardinal number that is the sum of six and one
digit, figure - one of the elements that collectively form a system of numeration; "0 and 1 are digits"
References in periodicals archive ?
The peptide, called heptad repeat 2 (HR2P), has "good potential" for development into a future drug against Mers, it says.
Robert Gordis, "The Heptad as an Element of Biblical and Rabbinic Style," Journal of Biblical Literature, 62:1 (March 1943) pp.
T-Cells Edited To Express the C34 Peptide from gp41 Heptad Repeat-2 Fused to CCR5 or CXCR4 Exhibit Robust Protection from Diverse HIV-1 Isolates.