An Arc

(astronomy) That part of a circle which a heavenly body appears to pass through as it moves above and below the horizon. [from 14th c.]
(geometry) A continuous part of the circumference of a circle (circular arc) or of another curve. [from 16th c.]
A curve, in general. [from 17th c.]
A band contained within parallel curves, or something of that shape. [from 17th c.]
(electrics) A flow of current across an insulating medium; especially a hot, luminous discharge between either two electrodes or as lightning. [from 19th c.]
A story arc. [from 20th c.]
(mathematics) A continuous mapping from a real interval (typically [0, 1]) into a space.
(graph theory) A directed edge.
(basketball, slang) The three-point line.
(film) An arclight.