1. A full, rich outpouring of harmonious sound.
2. The entire range of an instrument or voice.
3. Either of the two principal stops on a pipe organ that form the tonal basis for the entire scale of the instrument.
4. The interval and the consonance of an octave.
5. A standard indication of pitch.
6. A tuning fork.

[Middle English diapasoun, from Latin diapāsōn, the whole octave, from Greek dia pāsōn (khordōn), through all (the notes) : dia, through; see dia- + pāsōn, feminine genitive pl. of pās, every.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.