Arc: Part of a circle; the curve between two points on a circle.

If circle is divided into two unequal parts or arcs, the shorter arc (in red) is called the minor arc and the longer arc (in blue) is called the major arc.

Note that a semicircle is an arc that makes up half of a circle. A line containing the diameter of a circle separates the circle into two semicircles. In the figure below, the line EF, which contains the diameter of
circle A, divides the circle into two semi-circles, arc EGF and arc
EHF.