Tropic

in geography, one of two parallels of latitude situated 23 1/2 degree from the equator. That north of the equator is the tropic of Cancer; the southern is the Tropic of Capricorn. The term tropic signifies to turn or change, having reference to the limit beyond which the vertical rays of the sun never pass. The Tropic of Cancer and the Tropic of Capricorn include a belt 47 degree wide known as the Torrid Zone. The tropics is used to designate the regions within or near these two lines.