A two-dimensional geometric figure, a line, consisting of the set of all those points in a plane that are equally distant from a given point (center).
The set of all points (x, y) such that (x − 1)2 + y2 = r2 is a circle of radius r around the point (1, 0).
2
A two-dimensional geometric figure, a disk, consisting of the set of all those points of a plane at a distance less than or equal to a fixed distance (radius) from a given point.
3
Any shape, curve or arrangement of objects that approximates to or resembles the geometric figures.
Children, please join hands and form a circle.
4
A specific group of persons; especially one who shares a common interest.