An arc which is more than half of the circle is called

An arc which is more than half of the circle is called  major arc.

A major arc is an arc whose points are on (or) in the exterior of a central angle. The measure of a major arc is equal to $360°$  minus the measure of its central angle.

                               

$m\stackrel{⌢}{ADC}=360°-m\angle ABC$

$=360°-x$