Arc

The term "arc" is used in mathematics in several senses. In topology, an arc in a topological space is a subspace homeomorphic to the closed interval . Equivalently, is the image of a homeomorphism . Such a homeomorphism is a path, but not every path is a homeomorphism onto its image. The length of a rectifiable arc is its arc length.

In graph theory, a graph arc is an ordered pair of adjacent vertices. The word is also sometimes used for a path through a graph that passes through no graph vertex twice (Gardner 1984, p. 96).

In plane geometry, the corresponding portion of the circumference of a circle is a circular arc.

The prefix "arc" is also used to denote the inverse functions of trigonometric functions and hyperbolic functions.