An Etymological Dictionary of Astronomy and Astrophysics

A → flash of light produced by an → electric discharge in response to the buildup of an → electric potential between → cloud and → Earth’s surface, or between different portions of the same cloud.

Etymology (EN): Lightning, pr.p. of lightnen “make bright,” extended form of O.E. lihting, from leht, → light.

Etymology (PE): Âzaraxš, from âzar “fire,” variants âtaš, taš (Mid.Pers. âtaxš, âtur “fire;” Av. ātar-, āθr- “fire,” singular nominative ātarš-; O.Pers. ātar- “fire;” Av. āθaurvan- “fire priest;” Skt. átharvan- “fire priest;” cf. L. ater “black” (“blackened by fire”); Arm. airem “burns;” Serb. vatra “fire;” PIE base *āter- “fire”) +
raxš “lightning, reflection of light,” raxšidan “to shine, flash,” variant deraxš, deraxšidan “to shine, radiate”
(O.Pers. raucah-, Av. raocah- “light” (cf. Skt. roka- “brightness, light,” Gk. leukos “white, clear,” L. lux “light” (also lumen, luna), E. light, Ger. Licht, Fr. lumière;
PIE base *leuk- “light, brightness”); cognate with Mod.Pers. words
ruz “day,” rowšan “bright, clear,” foruq “light,” and afruxtan “to light, kindle”).