incandescence (n.)

"glowing with heat, rendered luminous by heat," 1794, from French incandescent (18c.) or directly from Latin incandescentem (nominative incandescens), present participle of incandescere "become warm, glow, kindle," from in- "within" (from PIE root *en "in") + candescere "begin to glow, become white," inceptive of candere "to glow, to shine" (from PIE root *kand- "to shine"). In reference to electric light, from 1881. The verb incandesce (1838), originally in science, is perhaps a back-formation.

also *kend-, Proto-Indo-European root meaning "to shine."

It forms all or part of: candela; candelabrum; candescent; candid; candidate; candle; candor; chandelier; chandler; frankincense; incandescence; incandescent; incendiary; incense (n.) "substance producing a sweet smell when burned;" incense (v.1) "to provoke, anger."

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit cand- "to give light, shine," candra- "shining, glowing, moon;" Greek kandaros "coal;" Latin candere "to shine;" Welsh cann "white," Middle Irish condud "fuel."