great circle

plural great circles

1. geometryA circle defined as the intersection of the surface of a sphere and a plane which passes through the centre of the sphere.
2. A segment of such circle representing the shortest distance between two points on the surface of a sphere.

   Because the Earth's surface is curved, the shortest distance is actually a curve over the surface called a great circle.

   2005, Phil Medina, Homework Helpers: Earth Science, page 52

   2 more examples

   Wherever a navigator may be, it certainly would be to his advantage to be able to find the great circle, or shortest course, and the distance, to his port of destination, [....]

   1902, S. L. Penfield, “Use of the Stereographic Projection for Geographical Maps and Sailing Charts”, in American Journal of Science

   The shortest distance between two points on an ocean Mercator chart is not a straight line - it is a curve known as a 'great circle'.

   2003, Jeff Toghill, The Navigator's Handbook: Essential Methods and Equipment--and how to Use Them

   Synonyms: great-circle arc