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newspaper (and now information technology) slang for "unit of writing that can be used over and over without change," 1893, from a literal meaning (1840) "metal rolled in large, flat plates for use in making steam boilers." The connecting notion is probably of sturdiness or reusability. From 1890s to 1950s, publicity items were cast or stamped in metal ready for the printing press and distributed to newspapers as filler. The largest supplier was Western Newspaper Union.