in music, a musical interval, by which most authors who have wrote on the theory of music, use to express the octave of the Greeks.

among the musical instrument-makers, a kind of rule or scale whereby they adjust the pipes of their organs, and cut the holes in their hautboys, flutes, &c. in due proportion for performing the tones, semitones, and concords, just.

DIAPASON-Diæx, in music, a kind of compound concord, whereof there are two sorts; the greater, which is in the proportion of 10-3; and the lesser, in that of 16-5.