Origin and history of moonlight

"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 meaning "something used for igniting" is from 1680s. The sense of "a consideration which puts something in a certain view" (as in in light of) is from 1680s. As short for traffic light from 1938.

The figurative spiritual sense was in Old English; the sense of "mental illumination" is recorded by mid-15c. Quaker use is by 1650s; New Light/Old Light in church doctrine also is from 1650s.

Omnia, quae sunt, lumina sunt [Scotus Erigena (810?-877?) "All things that are, are light"]

The 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.

"heavenly body which revolves about the earth monthly," Middle English mone, from Old English mona, from Proto-Germanic *menon- (source also of Old Saxon and Old High German mano, Old Frisian mona, Old Norse mani, Danish maane, Dutch maan, German Mond, Gothic mena "moon"), from PIE *me(n)ses- "moon, month" (source also of Sanskrit masah "moon, month;" Avestan ma, Persian mah, Armenian mis "month;" Greek mene "moon," men "month;" Latin mensis "month;" Old Church Slavonic meseci, Lithuanian mėnesis "moon, month;" Old Irish mi, Welsh mis, Breton miz "month"), from root *me- (2) "to measure" in reference to the moon's phases as an ancient and universal measure of time.

A masculine noun in Old English. In Greek, Italic, Celtic, and Armenian the cognate words now mean only "month." Greek selēnē (Lesbian selanna) is from selas "light, brightness (of heavenly bodies)." Old Norse also had tungl "moon" ("replacing mani in prose" - Buck), evidently an older Germanic word for "heavenly body," cognate with Gothic tuggl, Old English tungol "heavenly body, constellation," of unknown origin or connection. Hence also Old Norse tunglfylling "lunation," tunglœrr "lunatic" (adj.).

Moon was extended 1665 to satellites of other planets. As typical of a place impossible to reach or a thing impossible to obtain, by 1590s. The meaning "a month, the period of the revolution of the moon about the earth" is from late 14c.

The moon race and the U.S. space program of the 1960s inspired coinages, including, from those skeptical of the benefits to be gained, moondoggle (based on boondoggle).

The man in the moon "fancied semblance of a man seen in the disk of the full moon" is mentioned since early 14c.; he carries a bundle of thorn-twigs and is accompanied by a dog. Some Japanese, however, see a rice-cake-making rabbit in the moon. The old moon in the new moon's arms (1727) is the appearance of the moon in the first quarter, in which the whole orb is faintly visible by earthshine.

early 15c., "moonlight, the shining of the moon," from moon (n.) + shine (n.). Similar formation in Dutch maneschijn, German Mondschein, Swedish månsken, Danish maaneskin. In a figurative use, "appearance without substance, pretense, fiction" from late 15c.; perhaps from the notion of "moonshine in water" (see moonraker) or "light without heat."

Meaning "illicit or smuggled liquor" is attested from 1785 (earliest reference is to that smuggled on the coasts of Kent and Sussex; in reference to Southern U.S., by 1829), from the notion of being brought in or taken out under cover of darkness at night. Moonlight also occasionally was used in this sense early 19c. As a verb in this sense from 1883. Related: Moonshiner "smuggler; one who pursues a dangerous or illegal trade at night" (1860).