What is the meaning of Equator?

An imaginary great circle around Earth, equidistant from the two poles, and dividing earth's surface into the northern and southern hemispheres.

A similar great circle on any sphere, especially on a celestial body, or on another reasonably symmetrical three-dimensional body.

The midline of any generally spherical object, such as a fruit or vegetable, that has identifiable poles.

The celestial equator.

equator (great circle, equidistant from the poles, on Earth or another sphere)

Source: wiktionary.org