noun

1. Historical the part of a circle that is the apparent path of a heavenly body above and below the horizon
2. a bowlike curved line or object
3. 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
4. Geom.
   1. any part of a curve, esp. of a circle
   2. the angular measurement of this

Etymology: ME ark < OFr arc < L arcus, a bow, arch < IE base *arqu-, bowed, curved > arrow

adjective

intransitive verb arced or arcked, arcing arc′·ing or arcking arck′·ing

1. to move in a curved course
2. Elec. to form an arc