A combining form from Gr. \"epta`, seven.
n.
A system of seven sounds.
n.
A lyre with seven chords.
n.
A composition sung to the sound of seven chords or tones.
n.
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.
n.
The sum or number of seven.
n.
A book in seven languages.
n.
A plane figure consisting of seven sides and having seven angles.
a.
Having seven angles or sides.
n. pl.
A Linnaean order of plants having seven pistils.
n.
A solid figure with seven sides.
a.
Consisting of seven parts, or having the parts in sets of sevens.
n. pl.
A Linnaean class of plants having seven stamens.
n.
Any one of several isometric hydrocarbons, C7H16, of the paraffin series (nine are possible, four are known); -- so called because the molecule has seven carbon atoms. Specifically, a colorless liquid, found as a constituent of petroleum, in the tar oil of cannel coal, etc.
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