Canonically, a circle is the set of points equidistant from a given point (the center of the circle). The set of points inside the circle is known as a disc. Ge

Canonically, a circle is the set of points equidistant from a given point (the center of the circle). The set of points inside the circle is known as a disc. Generalizing slightly, a circle is a 1-sphere and a disc is a ball in 2 dimensions. So no, the post has it correct. In fact, circumference is the scalar value corresponding to the length of the circle. This relies on significantly more structure (i.e. having a metric) than the terms circle and disc.