Definition of great circle
: a circle formed on the surface of a sphere by the intersection of a plane that passes through the center of the sphere; specifically : such a circle on the surface of the earth an arc of which connecting two terrestrial points constitutes the shortest distance on the earth's surface between them
First Known Use of great circle
Learn More about great circle
Britannica.com: Encyclopedia article about "great circle"
Seen and Heard
What made you want to look up great circle? Please tell us where you read or heard it (including the quote, if possible).