A compass is a geometric tool used to draw circles.
A tool called a compass is often used to draw circles
A drafting compass
Compass compass compass
You use a compass to draw an accurate circle.
Most of the time, a tool called a "compass" is used to draw perfect circles. This compass is not to be mistaken with a directional compass.
A compass is mainly used to draw perfect circles, but it can also be used to draw arcs of different sizes.