Etymology Borrowed from Latin līchēn, from Ancient Greek λειχήν (leikhḗn), from λείχω (leíkhō, “to lick”). Originally used of liverwort; the modern sense first recorded 1715.
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Any of many symbiotic organisms, being associations of algae and fungi, often found as white or yellow-to-blue–green patches on rocks, old walls, etc.
The Beaches of Lukannon–the winter wheat so tall, / The dripping, crinkled lichens, and the sea-fog drenching all!1894 May, Rudyard Kipling, “Lukannon”, in The Jungle Book, London; New York, N.Y.: Macmillan and Co., published June 1894, →OCLC, page 122:
It was the same rich green that one sees on forest moss or on the lichen in caves: plants which like these grow in a perpetual twilight.1895 May 29, H[erbert] G[eorge] Wells, chapter XI, in The Time Machine: An Invention, London: William Heinemann, →OCLC:
1 more example
The nibble marks of the stone adze were still visible, though crusted over with scale lichens in most places.1915, John Muir, chapter V, in Travels in Alaska:
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Figuratively Something which gradually spreads across something else, causing damage.
Meanwhile, abiding a day of judgment, she fought ceaselessly to deny the bitter drops in her cup, to tear back the slow, the intangibly slow growth of a hot, corrosive lichen eating into her heart.1912 January, Zane Grey, “Shadows on the Sage-slope”, in Riders of the Purple Sage […], New York, N.Y.; London: Harper & Brothers Publishers, →OCLC, page 202:
Etymology Borrowed from Latin līchēn, from Ancient Greek λειχήν (leikhḗn), from λείχω (leíkhō, “to lick”). Originally used of liverwort; the modern sense first recorded 1715.
1
To cover with lichen.
[…] making the rocks assume the mould of age and lichening the trees with damp beauty.1903, J. Gordon Mowat, John Alexander Cooper, Newton MacTavish, The Canadian Magazine, volume 21, page 37: