nadir Meaning, Definition & Usage

  1. noun an extreme state of adversity; the lowest point of anything
    low-water mark.
  2. noun the point below the observer that is directly opposite the zenith on the imaginary sphere against which celestial bodies appear to be projected

WordNet

Na"dir noun
Etymology
F., Sp., & It. nadir; all fr. Ar. nasiru's samt nadir, prop., the point opposite the zenith (as samt), in which nasir means alike, corresponding to. Cf. Azimuth, Zenith.
Definitions
  1. That point of the heavens, or lower hemisphere, directly opposite the zenith; the inferior pole of the horizon; the point of the celestial sphere directly under the place where we stand.
  2. The lowest point; the time of greatest depression.
    The seventh century is the nadir of the human mind in Europe. Hallam.

Webster 1913