lamplight (n.)

c. 1200, "vessel containing flammable liquid and a wick to lift it by capillary action when lit," from Old French lampe "lamp, lights" (12c.), from Latin lampas "a light, torch, flambeau," from Greek lampas "a torch, oil-lamp, beacon-light, light," from lampein "to shine," perhaps from a nasalized form of PIE root *lehp- "to light, glow" (source also of Lithuanian lopė "light," Hittite lappzi "to glow, flash," Old Irish lassar "flame," Welsh llachar "glow").

Replaced Old English leohtfæt "light vessel." From 19c. in reference to gas and later electric lamps. To smell of the lamp "be a product of laborious night study," said disparagingly of a literary work, is attested from 1570s (compare midnight oil). The Greek stem lampad- formed a number of compounds, some in English, such as lampadomancy (1650s) "divination from variations in the flame of a lamp."

"brightness, radiant energy, that which makes things visible," Old English leht (Anglian), leoht (West Saxon), "light, daylight; spiritual illumination," from Proto-Germanic *leukhtam (source also of Old Saxon lioht, Old Frisian liacht, Middle Dutch lucht, Dutch licht, Old High German lioht, German Licht, Gothic liuhaþ "light"), from PIE root *leuk- "light, brightness."

The -gh- was an Anglo-French scribal attempt to render the Germanic hard -h- sound, which has since disappeared from this word. The figurative spiritual sense was in Old English; the sense of "mental illumination" is first recorded mid-15c. Meaning "something used for igniting" is from 1680s. Meaning "a consideration which puts something in a certain view" (as in in light of) is from 1680s. Short for traffic light from 1938. Quaker use is by 1650s; New Light/Old Light in church doctrine also is from 1650s. Meaning "person eminent or conspicuous" is from 1590s. A source of joy or delight has been the light of (someone's) eyes since Old English:

Ðu eart dohtor min, minra eagna leoht [Juliana].

Phrases such as according to (one's) lights "to the best of one's natural or acquired capacities" preserve an older sense attested from 1520s. To figuratively stand in (someone's) light is from late 14c. To see the light "come into the world" is from 1680s; later as "come to full realization" (1812). The rock concert light-show is from 1966. To be out like a light "suddenly or completely unconscious" is from 1934.