七弦琴,七音音階
Heptachord \Hep"ta*chord\, n. [Gr. "epta`xordos seven-stringed; "epta` seven + xordh` chord: cf. F. heptacorde. See {Seven}, and {Chord}.] 1. (Anc. Mus.) (a) A system of seven sounds. (b) A lyre with seven chords. 2. (Anc. Poet.) A composition sung to the sound of seven chords or tones. --Moore (Encyc. of Music).