moonlight

Etymology

From Middle English monelight, from Old English mōnan lēoht (“moonlight”, literally “moon's light, light of the moon”). Equivalent to moon + light. Cognate with Scots munelicht ~ muinlicht, West Frisian moanneljocht, Dutch maanlicht, German Mondlicht.

noun

1. (sometimes attributive) The light reflected from the Moon.
   ’Tis eight o’clock,—a clear March night, The moon is up,—the sky is blue, The owlet, in the moonlight air, Shouts from nobody knows where; 1798, William Wordsworth, The Idiot Boy, lines 1–4
   It was the pensive oysterman that saw a lovely maid, Upon a moonlight evening, a-sitting in the shade; 1830, Oliver Wendell Holmes, Ballad of the Oysterman, lines 5–6
   […] What say you, gentlemen, shall we have a moonlight hunt? 1889, Robert Louis Stevenson, chapter 12, in The Master of Ballantrae
   1957, Sylvia Dee, “Moonlight Swim” (song recorded by Nick Noble and Elvis Presley), Let’s go on a moonlight swim Far away from the crowd All alone upon the beach Our lips and our arms Close within each other’s reach Will be on a moonlight swim
   On a moonlight night it would be different. The happy voices of children playing in open fields would then be heard. And perhaps those not so young would be playing in pairs in less open places, and old men and women would remember their youth. 1958, Chinua Achebe, chapter 2, in Things Fall Apart, London: William Heinemann

verb

1. To work on the side (at a secondary job), often in the evening or during the night.
   There are three individual rear seats. They all slide, they all fold, or they can all be removed completely, so that you can moonlight as a van. 2004 July, Richard Porter, Paul Kerensa, “MPVs as minicabs” (00:22:29 from the start), in Top Gear (2002 TV series), season 4, episode 7, James D. May (actor), United Kingdom, Isle of Man, Channel Islands, via BBC Two, →OCLC
   Believing the bones to belong to a cave bear, the quarry owner passed them on to a local schoolteacher, Johann Carl Fuhlrott, who moonlighted as a fossilist. 2014, Elizabeth Kolbert, The Sixth Extinction: An Unnatural History, Picador, page 240
2. (by extension) To engage in an activity other than what one is known for.
3. (by extension, of an inanimate object) To perform a secondary function substantially different from its supposed primary function, as in protein moonlighting.
4. (Britain, dated) To carry out undeclared work.