HEPTAD
Hep"tad, n. Etym: [L. heptas the number seven. Gr. "epta` seven.]
(Chem.)
Defn: 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.
HEPTADE
Hep"tade, n. Etym: [Cf. F. heptade. See Heptad.]
Defn: The sum or number of seven.
HEPTAGLOT
Hep"ta*glot, n. Etym: [Gr. "epta` seven + 3,
Defn: A book in seven languages.
HEPTAGON
Hep"ta*gon, n. Etym: [Gr. "epta` seven + heptagone.] (Geom.)
Defn: A plane figure consisting of seven sides and having seven angles.
HEPTAGONAL
Hep*tag"o*nal, a. Etym: [Cf. F. heptagonal.]
Defn: Having seven angles or sides. Heptagonal numbers (Arith.), the numbers of the series 1, 7, 18, 34, 55, etc., being figurate numbers formed by adding successively the terms of the arithmetical series 1, 6, 11, 16, 21, etc.