Final answer:
A great circle route is the shortest distance an object can travel between two points on the curved surface of the Earth.
Step-by-step explanation:
A great circle route marks the shortest distance that an object can travel between two points on the curved surface of the Earth. When traveling from one point to another, such as from Chicago to Rome, the shortest distance is not a straight line but the arc of a great circle. A great circle is a circle on the surface of a sphere, such as Earth, with its center at the center of the sphere. The Earth's equator is an example of a great circle. It is halfway between the North and South Poles and is a line of latitude that forms a circle around the Earth.