tetrachordon
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tetrachordorum Noun: neuter genitive plural of tetrachordon
tĕtrăchordŏn, ī, n. (τετράχορδον), ¶ 1 tétracorde, succession diatonique de quatre tons : Vitr. Arch. 6, 4 ; Capel. 9, 935 ¶ 2 réunion de quatre : Varro Men. 458.
Tetrachordon
(τετράχορδον). A word meaning literally “four-stringed,” and hence “having four notes.” A scale comprising two tones and a half, which formed the old Greek musical system. The word does not mean any special instrument of music. Vitruvius applies the term to a waterorgan (hydraulus) when it had only four barrels (x. 8, 2). See hydraulus.