/ ˈpɪnəfɔː(r); NAmE / noun
1.
(also ˈpinafore dress ) (both especially BrE ) ( NAmE usually jumper ) a loose dress with no sleeves, usually worn over a blouse or sweater
2.
( old-fashioned ) (also informal pinny ) (both BrE ) a long loose piece of clothing without sleeves, worn by women over the front of their clothes to keep them clean, for example when cooking
—compare apron
3.
a loose piece of clothing like a dress without sleeves, worn by children over their clothes to keep them clean, or by young girls over a dress
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WORD ORIGIN
late 18th cent.: from pin + afore before (because the term originally denoted an apron with a bib pinned on the front of a dress).