Arctic and Arctic circle

Arctic noun - The regions to the north of the Arctic Circle centered on the North Pole.

Arctic circle and arctic are semantically related. in far north topic. In some cases you can use "Arctic circle" instead a noun "Arctic".

Arctic circle noun - A line of latitude near but to the south of the north pole; 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.

Arctic and Arctic circle are semantically related. Sometimes you can replace term "Arctic" with "Arctic circle", this terms are similar.