A hexachord is a collection of six musical notes. The term derives from the Greek word , a compound of á¼Âþ (hex, six) and ÃÂÿÃÂôî (chordÃÂ).
Since the 11th century, hexachords have been used in music pedagogy. Guido of Arezzo is the nominal creator of a learning system that relied on a six-note scale to facilitate rapid learning of melodies. Hexachord also could refer to the musical interval of a sixth.
In the 20th century, music theorists broadened the definition of the hexachord into any collection of six notes. The notes did not need to be contiguous members of a scale or tone row. David Lewin used the term in this sense as early as 1959. Carlton Gamer uses hexachord and hexad interchangeably.