ARCTICK CIRCLE, is a lesser circle of the sphere, parallel to the equator, and 23° 30’ distant from the North Pole; from whence its name. See CIRCLE and SPHERE.

This, and its opposite, the Antarctic, are called the two polar circles; and may be conceived to be described by themotion of the poles of the ecliptic, around the poles of theequator, or of the world. See POLE and POLAR.