di·a·pa·son (dī′ə-pāzən, -sən)
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.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.