Definition:Circle/Semicircle

Definition

 * Circle.png

In the above diagram, the region bounded by the straight line segment $CD$ and the arc $DBC$ is a semicircle.

Also, the region bounded by the straight line segment $CD$ and the arc $DFEC$ is a semicircle.

Also known as
A semicircle is also seen referred to as a hemicycle, but this is uncommon.