Heptachord :: Heptachord (n.) A composition sung to the sound of seven chords or tones.
Heptad :: Heptad (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..
Heptade :: Heptade (n.) The sum or number of seven.
Heptaglot :: Heptaglot (n.) A book in seven languages.
Heptagon :: Heptagon (n.) A plane figure consisting of seven sides and having seven angles.
Heptagonal :: Heptagonal (a.) Having seven angles or sides.
Heptagynia :: Heptagynia (n. pl.) A Linnaean order of plants having seven pistils.
Heptane :: Heptane (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..