lour

Etymology

The verb is derived from Middle English louren, lour, loure (“to frown or scowl; to be dark or overcast; to droop, fade, wither; to lurk, skulk”), probably from Old English *lūran, *lūrian, from Proto-Germanic *lūraną (“to lie in wait, lurk”). The English word is cognate with Danish lure (“to lie in ambush; to take a nap”), Middle Dutch loeren (modern Dutch loeren (“to lurk, spy on”)), Middle Low German lūren (“to lie in ambush”), German Low German luren (“to lurk”), Middle High German lūren (“to lie in ambush”) (modern German lauern (“to lie in ambush; to lurk”)), Icelandic lúra (“to take a nap”), Saterland Frisian luurje (“to lie in wait”), West Frisian loere (“to lurk”), and Swedish lura (“to lie in ambush; to deceive, fool, trick; to lure; to take a nap”); and is related to lurk. The noun is derived from the verb.

verb

1. (intransitive) To frown; to look sullen.
   Their lank black hair hung round their black visages; and the only points of relief in the wild countenance which loured from under their strange head-dresses, were the dark, piercing eyes, and the white teeth. 1840 May, “Art. V.—Travels in Koordistan and Mesopotamia. By Ja[me]s Baillie Fraser. London: 1840.”, in The Dublin Review, volume VIII, number XVI, London: C[harles] Dolman, […] (Nephew and successor to J. Booker.)[…], →OCLC, page 432
2. (intransitive, figurative) To be dark, gloomy, and threatening, as clouds; of the sky: to be covered with dark and threatening clouds; to show threatening signs of approach, as a tempest.
   Weather in Auguſt, 1787. … dark, louring, cool, briſk ſhower. 1788 July, “Meteorological Diaries for July, 1788; and for August, 1787”, in Sylvanus Urban [pseudonym; Edward Cave], editor, The Gentleman’s Magazine, and Historical Chronicle, volume XXV, London: Printed by John Nichols, for D. Henry,[…], published January 1755, →OCLC, page 570
   And still when loudliest howls the storm, / And darkliest lowers his native sky, / The king's fierce soul is in that form, / The warrior's spirit threatens nigh! 1846, R[obert] S[tephen] Hawker, “The Wreck”, in Echoes from Old Cornwall, London: Joseph Masters,[…], →OCLC, stanza X, page 76
   The queen's letter coming up to the duchess's own ideas of her own deserts, she condescended to speak on the subject which had caused such portentous blackness to lour on her countenance, on her first meeting her royal mistress. 1873, Agnes Strickland, chapter VIII, in Lives of the Queens of England, from the Norman Conquest. … In Six Volumes, new revised and augmented edition, volume VI, London: Bell & Daldy,[…], →OCLC, page 285
   Seek to be prosperous; once let fortune lour, and the aid supplied by friends is naught. 1891, Euripides, “The Phœnician Maidens”, in Edward P[hilip] Coleridge, transl., The Plays of Euripides: Translated into English Prose from the Text of Paley (Bohn’s Classical Library), volume II, London: George Bell & Sons,[…], →OCLC, page 230

noun

1. A frown, a scowl; an angry or sullen look.
   I have ſuch averſion to ill temper, that I could ſooner forgive my wife adultery, than croſſneſs. I cannot taſte Caſſio's kiſs on her lips; but I can ſee a lour on her brow. 1798, attributed to Richard Griffith or Laurence Sterne, The Koran: Or, Essays, Sentiments, Characters, and Callimachies, of Tria Juncta in Uno, M.N.A. or Master of No Arts. Three Volumes Complete in One, volume II, Vienna: Printed for R[udolf] Sammer, bookseller, →OCLC, paragraph 49, page 156
2. (figurative) Of the sky, the weather, etc.: a dark, gloomy, and threatening appearance.