—n. 1. Geom.any unbroken part of the circumference of a circle or other curved line.
2. Also called electric arc.Elect.a luminous bridge formed in a gap between two electrodes. Cf. spark1 (def. 2).
3. Astron.the part of a circle representing the apparent course of a heavenly body.
4. anything bow-shaped.
—v.i. 1. to form an electric arc.
2. to move in a curve suggestive of an arc.