'Tetrachord' definitions:
Definition of 'Tetrachord'
From: GCIDE
- Tetrachord \Tet"ra*chord\, n. [L. tetrachordon, Gr. ?, from ? four-stringed; te`tra- (see Tetra-) + ? a chord: cf. F. t['e]trachorde.] (Anc. Mus.) 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. [1913 Webster]