Circumference
The circumference is the total distance around the outside edge of a circle. It is the specific term used for the perimeter of a circular two-dimensional shape.
Example
The circumference $C$ of a circle with a radius $r$ is calculated using the formula $C = 2\pi r$. For a circle with a radius of $5 \text{ cm}$ and taking $\pi \approx 3.14$: $$C = 2 \times 3.14 \times 5 = 31.4 \text{ cm}$$