na·dir (nādər, -dîr′)
1. Astronomy A point on the celestial sphere directly below the observer, diametrically opposite the zenith.
2. The lowest point: the nadir of their fortunes.
[Middle English, from Medieval Latin, from Arabic naẓīr (as-samt), opposite (the zenith), from naẓara, to see, watch; see nr in the Appendix of Semitic roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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.