2. Concord, as of notes an octave apart; harmony.
The fair music that all creatures made . . . In
perfect diapason. --Milton.
3. The entire compass of tones.
Through all the compass of the notes it ran, The
diapason closing full in man. --Dryden.
4. A standard of pitch; a tuning fork; as, the French normal
diapason.
5. One of certain stops in the organ, so called because they
extend through the scale of the instrument. They are of
several kinds, as {open diapason}, {stopped diapason},
{double diapason}, and the like.