noun

• (geography, often “the Equator”) An imaginary great circle around Earth, equidistant from the two poles, and dividing earth's surface into the northern and southern hemisphere.
• (astronomy) A similar great circle on any sphere, especially on a celestial body, or on other 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.
• (geography) Earth’s equator.