It is an arc that is formed by two segments that intercept the circle. These segments intersect at at point on the circle, or inside, or outside the circle forming an angle. The angle that intercepts the arc determine the measure of the arc, or vise versa.
There are also arcs intercepted by parallel lines or pair of segments/chords that intersect the circle. The two intercepted arcs are opposite and congruent.
It is important to note that the intercepted arc is a section or portion of the circumference of the circle for the purpose of determining its length in degrees.