arc

To arc means to make a curved shape or move in a curved path. (verb)

An example of arc is the way stars move across the sky.

An arc is a curve or bowed shape, like a part of a circle. (noun)

An example of an arc is a rainbow.

See arc in Webster's New World College Dictionary

noun

Historical the part of a circle that is the apparent path of a heavenly body above and below the horizon
a bowlike curved line or object
Elec. the band of sparks or incandescent light formed when an electric discharge is conducted from one electrode or conducting surface to another, characterized by relatively high current and low potential difference between electrodes
Geom.
1. any part of a curve, esp. of a circle
2. the angular measurement of this

adjective

designating an inverse trigonometric function: arc sine x is an angle whose sine is x

intransitive verb arced or arcked, arcing or arcking