Equator
WordNet
noun
(1) An imaginary line around the Earth forming the great circle that is equidistant from the north and south poles
"The equator is the boundary between the northern and southern hemispheres"
(2) A circle dividing a sphere or other surface into two usually equal and symmetrical parts
WiktionaryText
Noun
- An imaginary great circle around the earth, equidistant from the two poles, and dividing earth's surface into the northern and southern hemisphere.
- A similar great circle on any sphere, especially on a celestial body, or on other reasonably symmetrical three-dimensional body.
- A short form of the celestial equator.