Arc

Arc is a curving trajectory, or something in a shape of a curve.

In mathematics, arc is a curve that is part of the circumference of a circle. As modifier, it is used to indicate the inverse of a trigonometrical function. Formerly, there was a method of defining trigonometrical functions by arc, hence the usage.

In electricity, a luminous electric discharge between two electrodes or other points is called an electric arc.

In literature, such as an emotional arc, is the principal theme, the resolution of the narrative, or the development in a story, novel, play, or movie is also called an arc.