[dahy-uh-pey-zuh n, -suh n] /ˌdaɪ əˈpeɪ zən, -sən/
a full, rich outpouring of melodious sound.
the compass of a voice or instrument.
a fixed standard of pitch.
either of two principal timbres or stops of a pipe organ, one of full, majestic tone (open diapason) and the other of strong, flutelike tone (stopped diapason)
any of several other organ stops.
a tuning fork.
1350-1400;Middle Englishdiapasoun < Latindiapāsōn the whole octave < Greekdià pāsôn (chordôn) through all (the notes), short for hē dià pāsôn chordôn symphōnía the concord through all the notes of the scale