Definitions
1.NounAn imaginary great circle around Earth, equidistant from the two poles, and dividing earth's surface into the northern and southern hemispheres.
2.NounA similar great circle on any sphere, especially on a celestial body, or on another reasonably symmetrical three-dimensional body.
3.NounThe midline of any generally spherical object, such as a fruit or vegetable, that has identifiable poles."Slice the onion through the equator."
4.NounThe celestial equator.