noun
large circle
General term for a circle of large size, not necessarily mathematical.
グラウンドに大円を描く。
Draw a large circle on the ground.
noun
great circle
Mathematical term: a circle on a sphere whose plane passes through the center of the sphere. Contrasts with 小円 (small circle).
See also: 小円
赤道は地球の大円の一つである。
The equator is one of the Earth's great circles.