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great circle - Any circle on the surface of a sphere that lies on a plane through its center, or a circle that divides into two equal parts—as the Equator. More...
quadrant - A quarter of a circle or sphere. More...
rhumb line - A line on a sphere that cuts all meridians at the same angle; the path taken by a ship or plane that maintains a constant compass direction. More...
diameter - From Greek, meaning "measure through" (a circle or sphere, etc.). More...