equinox : Idioms & Phrases

• noun September 22
  fall equinox; autumnal equinox.
  
• noun (astronomy) the equinoctial point that lies in the constellation of Virgo
  

WordNet

• the time when the sun crosses the equator, as it proceeds southward, or when it passes the ~ point.

Webster 1913

• (Astron.), the difference between the mean and apparent places of the equinox.

Webster 1913

• noun September 22
  fall equinox; autumnal equinox.
  

WordNet

• noun March 21
  March equinox; spring equinox.
  

WordNet

• noun a slow westward shift of the equinoxes along the plane of the ecliptic caused by precession of the Earth's axis of rotation
  

WordNet

• (Astron.), the slow backward motion of the equinoctial points along the ecliptic, at the rate of 50.2&sec; annually, caused by the action of the sun, moon, and planets, upon the protuberant matter about the earth's equator, in connection with its diurnal rotation; so called because either equinox, owing to its westerly motion, comes to the meridian sooner each day than the point it would have occupied without the motion of precession, and thus precedes that point continually with reference to the time of transit and motion.

Webster 1913

• noun September 22
  fall equinox; autumnal equinox.
  

WordNet

• noun March 21
  March equinox; spring equinox.
  

WordNet

• noun March 21
  March equinox; spring equinox.
  
• noun (astronomy) the equinoctial point that lies in the constellation of Pisces
  

WordNet

• (Astron.), the time when the sun crosses the equator when proceeding northward.

Webster 1913