D defs.my
Entry 1 sense Webster, 1913

Tetrachord

· Tet·ra·chord · IPA
01 n. A scale series of four sounds, of which the extremes, or first and last, constituted a fourth. These extremes were immutable; the two middl…
  1. 1.
    A scale series of four sounds, of which the extremes, or first and last, constituted a fourth. These extremes were immutable; the two middle sounds were changeable.(Anc. Mus.)