Nadir

n. point opposite the zenith and directly below the observer; lowest point, base point (Astronomy)

For other uses, see Nadir (disambiguation). The nadir (from Arabic ﻧـدﻳﺭ nadeer نظير nathir, "opposite") is the astronomical term for the point in the sky directly below the observer, or more precisely, the point in the sky with an inclination of −90°. In simple terms, if you are standing on the earth, it is the direction "down" toward your feet.
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Noun
1. an extreme state of adversity; the lowest point of anything
(synonym) low-water mark
(hypernym) adversity, hardship, hard knocks
2. the point below the observer that is directly opposite the zenith on the imaginary sphere against which celestial bodies appear to be projected
(antonym) zenith
(hypernym) celestial point
(part-holonym) celestial sphere, sphere, empyrean, firmament, heavens, vault of heaven, welkin

n. nadir, point opposite the zenith and directly below the observer; (Astronomy) lowest point, base point

n. nadir, point opposite the zenith and directly below the observer; lowest point, base point (Astronomy)