Definition that contains great circle
- horizon the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth
- equator an imaginary line around the Earth forming the great circle that is equidistant from the north and south poles
- meridian an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator
- ecliptic the great circle representing the apparent annual path of the sun; the plane of the Earth's orbit around the sun; makes an angle of about 23 degrees with the equator
- geodesic (mathematics) the shortest line between two points on a mathematically defined surface (as a straight line on a plane or an arc of a great circle on a sphere)
- celestial equator the great circle on the celestial sphere midway between the celestial poles
- riemannian geometry (mathematics) a non-Euclidean geometry that regards space as like a sphere and a line as like a great circle
- geodesic line (mathematics) the shortest line between two points on a mathematically defined surface (as a straight line on a plane or an arc of a great circle on a sphere)
- equinoctial the great circle on the celestial sphere midway between the celestial poles
- vertical circle a great circle on the celestial sphere passing through the zenith and perpendicular to the horizon