Geometric Question:

A closed figure wherein points on the boundary are equidistant from the fixed center. More importantly, it's the shape of a pizza pie.
The set of all points in a plane that are exactly r units away from point O, where r is the radius and O is the center. The basis for such artifacts as wheels, wedding rings, and many types of cookies. We write "⊙O" to denote "the circle with center O."
A perfectly round two-dimensional shape. More technically, it's the set of all points that are the same distance away from another point (called the center).
A round conic defined by an eccentricity of 0. Also, a favorite shape for the terminally lost.