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.]
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