Dictionary
arc' light"
1. Also,arc' lamp".a lamp in which the light source is a high-intensity electric arc either between carbon rods in air or between metal electrodes in a xenon gas atmosphere enclosed in a quartz bulb.
2. the light produced by such a lamp. Cf.
carbon arc, xenon arc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.