/ ˈdaɪəpə(r); NAmE ˈdaɪpər/ noun
( NAmE ) = nappy :
a diaper rash
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WORD ORIGIN
Middle English : from Old French diapre , from medieval Latin diasprum , from medieval Greek diaspros (adjective), from dia across + aspros white. The term seems originally to have denoted a costly fabric, but after the 15th cent. it was used as as a noun to denote cotton or linen woven with a pattern of small diamonds; babies' nappies were originally made from pieces of this fabric, hence the current sense (late 16th cent.).