diezeugmenon means the last tetrachord, in the case where two tetrachords were placed separately from each other, but with only the interval of a tone between them. Lexicurio rates it Rare gem — a strength score of 82 out of 100.
Etymology
From Ancient Greek διεζευγμένων (diezeugménōn, “of the transposed (notes)”), aorist passive participle of διαζεύγνυμι (diazeúgnumi), from ζεύγνυμι (zeúgnumi).
noun
- The last tetrachord, in the case where two tetrachords were placed separately from each other, but with only the interval of a tone between them.“1914, Vitruvius (translated by Morris Hicky Morgan), Ten Books on Architecture
In the middle range, place first at the extreme ends the vessels which give the note of the chromatic hyperbolaeon; next to them, those which give the chromatic diezeugmenon, a fourth below; third, the chromatic synhemmenon; fourth, the chromatic meson, a fourth below; fifth, the chromatic hypaton, a fourth below; sixth”