Main Entry: equa·tor

Pronunciation: \i-ˈkwā-tər, ˈē-ˌ\

Function: noun

Etymology: Middle English, from Medieval Latin aequator, literally, equalizer, from Latin aequare

Date: 14th century

1 : the great circle of the celestial sphere whose plane is perpendicular to the axis of the earth
2 : a great circle of the earth or a celestial body that is everywhere equally distant from the two poles and divides the surface into the northern and southern hemispheres
3 a : a circle or circular band dividing the surface of a body into two usually equal and symmetrical parts b : equatorial plane <the equator of a dividing cell>
4 : great circle