equator
The great circle around the Earth, equidistant from the poles. Used in geography, climate, and everyday contexts.
Countries on the equator are hot all year round.
celestial equator
The projection of the Earth's equator onto the celestial sphere. Used in astronomy; often specified as 天の赤道.
See also: 天の赤道
The celestial equator is the projection of the Earth's equatorial plane onto the celestial sphere.
The ship crossed the equator and entered the Southern Hemisphere.
This country is located right on the equator.
low latitudes; equatorial region
equatorial radius