an imaginary line drawn parallel to the equator, at 23°28prime; S of the North Pole: between the North Frigid Zone and the North Temperate Zone.
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for arctic circle
the imaginary circle round the earth, parallel to the equator, at latitude 66° 32′ N; it marks the northernmost point at which the sun appears above the level of the horizon on the winter solstice
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Word Origin and History for arctic circle
1550s, in reference to a celestial circle, a line around the sky which, in any location, bounds the stars which are ever-visible from that latitude (in the Northern Hemisphere, this is focused on the celestial north pole); the concept goes back to the ancient Greeks, for whom this set of constellations included most prominently the two bears (arktoi), hence the name for the circle (see arctic). Of Earth, the circle 66 degrees 32 minutes north of the equator, marking the southern extremity of the polar day, it is recorded from 1620s.
Online Etymology Dictionary, © 2010 Douglas Harper
The parallel of latitude approximately 66°33′ north. It forms the boundary between the North Temperate and North Frigid zones.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Imaginary circle around the Earth about three-quarters of the way from the equator to the North Pole. North of this line is the “Land of the Midnight Sun,” where the sun never sets on the summer solstice.
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.