A very fine linen (or sometimes cotton) fabric with a rather open texture. Lawn is used for the sleeves of a bishop's official dress in the English Church, and, figuratively, stands for the office itself.
There would be mention of the bishops in their lawn sleeves, the judges in their ermine robes, the pillory, the stocks, the treadmill, the cat o’ nine tails, the Lord Mayor’s Banquet and the practice of kissing the Pope’s toe.
George Orwell. 1984 (1949)
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Perspiring in a loose lawn surplice with funnel sleeves he is seen, vergerfaced, above a rostrum about which the banner of old glory is draped. He thumps the parapet.