- Astronomy. the point on the celestial sphere directly beneath a given position or observer and diametrically opposite the zenith.
- Astrology. the point of a horoscope opposite the midheaven: the cusp of the fourth house.
- the lowest point; point of greatest adversity or despair.
Origin of nadir
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- the point on the celestial sphere directly below an observer and diametrically opposite the zenith
- the lowest or deepest point; depthsthe nadir of despair
Word Origin and History for nadiral
late 14c., in astronomical sense, from Medieval Latin nadir, from Arabic nazir "opposite to," in nazir as-samt, literally "opposite of the zenith," from nazir "opposite" + as-samt "zenith" (see zenith). Transferred sense of "lowest point (of anything)" is first recorded 1793.
- The point on the celestial sphere that is directly below the observer (90 degrees below the celestial horizon). Compare zenith.