Hexachord

Part of speech: noun

Definitions

1. A specific arrangement of six pitches that establishes a foundation for both melodic and harmonic structures in musical compositions
2. A theoretical framework composed of six distinct tones designed to facilitate the understanding of musical intervals and relationships
3. A system consisting of six unique notes that serves as the basis for creating melodies and harmonies in various musical contexts

Etymology: The most interesting part of this word is its musical history, which the source does not date, so I'll stick to the structure it gives. "Hexachord" is a compound: "hexa-", from Ancient Greek "hexa-" (the combining form of "hex", meaning six), joined to "chord", a word that in English came to mean a set of notes sounded together but which here means a sequence of notes. Together they name a scale of six notes. The "hexa-" element passed into English through Latin combining forms, which is why it appears in so many technical coinages, from "hexagon" to "hexameter." Its ultimate root is the Proto-Indo-European number word for six, which surfaces in Greek "hex" and Latin "sex" alike. The hexachord was a central tool of medieval and Renaissance music teaching, where singers learned to sight-read by mapping syllables onto six-note patterns. The name is a plain technical formation: a descriptive Greek-derived prefix attached to a musical term, naming the scale by its number of notes.