Definition of "nadir"

noun:
- The point of the celestial sphere, directly opposite the zenith; inferior pole of the horizon; point of the celestial sphere directly under the place where we stand.
  
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- The lowest point; time of greatest depression.
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License
- The axis of a projected conical shadow; the direction of the force of gravity at a location; down.
  
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- An empty box added beneath a full one in a beehive to give the colony more room to expand or store honey.
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License
verb:
- To extend (a beehive) by adding an empty box at the base.
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License