Etymology From Middle English louen, lowen (“rascal; rogue”), probably of Middle Dutch or Middle Low German origin. Compare Dutch loen (“simpleton”). Or, related to etymology 2, due to the bird's loud cry. Folk etymology associates it slang-wise with lunatic, though the latter may have influenced it; see loony.
An electric fire came next, followed by an umbrella and then a colander. "This bowl will carry no water," he muttered. "Some loon hath pierced it with holes."1971, Richard Carpenter, Catweazle and the Magic Zodiac, Harmondsworth: Puffin Books, page 67:
What's it like to be a loon? / I liken it to a balloon1971, Marc Bolan, “Cosmic Dancer”, in Electric Warrior, performed by T. Rex:
The diuell damne thee blacke, thou cream-fac'd Loone: Where got'ſt thou that Gooſe-looke.c. 1606 (date written), William Shakespeare, “The Tragedie of Macbeth”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act V, scene iii], page 149:
Ireland, Historical An English soldier of an expeditionary army in Ireland.
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Engineering, Natural sciences, Physical sciences, Traffic, Transport A round area of pavement that protrudes from one side of a road to accommodate turning vehicles with a wide turning circle.
Etymology Of North Germanic origin, from Old Norse lómr (“loon”), ultimately imitative of the bird's cry, particularly when it's in danger. Distantly related to lament, probably sharing Proto-Indo-European *leh₂- (expressive root).
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Canada, US Any of various birds, of the order Gaviiformes, of North America and Europe that dive for fish and have a short tail, webbed feet and a yodeling cry.
The Loone is an ill ſhap'd thing like a Cormorant; but that he can neyther goe nor flye; he maketh a noiſe ſometimes like a Sovvgelders horne.1634, William Wood, “Of the Birds and Fowles both of Land and Water”, in New Englands Prospect. A True, Lively, and Experimentall Description of that Part of America, Commonly Called New England; […], London: […] Tho[mas] Cotes, for Iohn Bellamie, […], →OCLC, 1st part, page 31:
[O]h, yes! the loon does shriek dreadfully - particularly when there's fine rain […]1886, Peter Christen Asbjørnsen, translated by H. L. Brækstad, Folk and Fairy Tales, page 286:
2 more examples
He came again to her and she said: ‘Run swifter than the deer, be more cunning than the beaver, dive deeper than the loon.’1903, Zane Grey, Betty Zane, New York, N.Y.: Grosset & Dunlap Publishers, →OCLC:
And I listened for a voice;— / But my heart was all I heard; / Not a screech-owl, not a loon, / Not a tree-toad said a word.1921, Edna St. Vincent Millay, “The Blue-Flag in the Bog”, in Second April: