Words related to *leuk-
late 13c., "affected with periodic insanity dependent on the changes of the moon," from Old French lunatique "insane," or directly from Late Latin lunaticus "moon-struck," from Latin luna "moon" (see luna).
Compare Old English monseoc "lunatic," literally "moon-sick;" Middle High German lune "humor, temper, mood, whim, fancy" (German Laune), from Latin luna. Compare also New Testament Greek selēniazomai "be epileptic," from selēnē "moon." Lunatic fringe (1913) was popularized and apparently coined by U.S. politician Theodore Roosevelt.
Then, among the wise and high-minded people who in self-respecting and genuine fashion strive earnestly for peace, there are foolish fanatics always to be found in such a movement and always discrediting it — the men who form the lunatic fringe in all reform movements. [Theodore Roosevelt, autobiography, 1913].
Earlier it was a term for a type of hairstyle worn over the forehead (1877). Lunatic soup (1918) was slang for "alcoholic drink" or several different alcoholic drinks drunk together.
"gloss, radiance, quality of shining by reflecting light," 1520s, from French lustre "gloss, radiance" (14c.), common Romanic (cognates: Spanish and Portuguese lustre, Rumanian lustru, Italian lustro "splendor, brilliancy"), a noun ultimately from Latin lustrare "spread light over, brighten, illumine," which is related to lustrum "purification" (from PIE *leuk-stro-, suffixed form of root *leuk- "light, brightness").
Especially "quality of glossiness or radiance in a textile material or fabric." Figurative meaning "radiant beauty" is from c. 1600; that of "splendor, renown" is from 1550s. Lusterware, also lustre-ware, "stoneware or crockery having surface ornamentations in metallic colors," is attested by 1820.
(plural lustra), "ceremonial purification of the Roman people every five years," 1580s, from Latin lustrum "a purificatory sacrifice, ceremony of purification; five-year period," from Proto-Italic *lustro- "expiation," which is of uncertain origin. Perhaps [OED] from root of luere "to wash" (from PIE root *leue- "to wash"). Or [Watkins, Klein], based on a possible earlier meaning "illumination," from PIE *leuk-stro-, from root *leuk- "light, brightness." De Vaan prefers as most likely the explanation "that lustrum was derived from *luH- 'to set free'," with suffix *-stro- also found in monstrum, etc.
"transparent, translucent, admitting the passage of light," 1610s, from Latin pellucidus "transparent," from pellucere "shine through," from per- "through" (from PIE root *per- (1) "forward," hence "through") + lucere "to shine" (from suffixed form of PIE root *leuk- "light, brightness"). Related: Pellucidly; pellucidity.