(n.) 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.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). tetrachord. Retrieved September 24, 2026, from http://smartdefine.org/tetrachord/definitions/2071538 |
| Chicago | Webster's. 2011. "tetrachord" http://smartdefine.org/tetrachord/definitions/2071538 (accessed September 24, 2026). |
| Harvard | Webster's 2011, tetrachord, Smart Define, viewed 24 September, 2026, <http://smartdefine.org/tetrachord/definitions/2071538>. |
| MLA | Webster's. "tetrachord" 28 May 2011. Web. 24 September 2026. <http://smartdefine.org/tetrachord/definitions/2071538> |