The parallel of latitude 66° 33ʹ north of the equator. It marks the northernmost point at which the sun is visible at the northern winter solstice and the southernmost point at which the midnight sun can be seen at the northern summer solstice.
北极圈
Definition of Arctic Circle in US English:
Arctic Circle
proper nounˈɑrktɪk ˌsərkəl
The parallel of latitude 66° 33ʹ north of the equator. It marks the northernmost point at which the sun is visible on the northern winter solstice and the southernmost point at which the midnight sun can be seen on the northern summer solstice.