■ noun
1》 (also Brit. ~ dress ) a collarless, sleeveless dress worn over a blouse or jumper.
2》 Brit. a woman's loose sleeveless garment worn over clothes to keep them clean.
3》 a sleeveless apron-like garment worn over a young girl's dress, fastening at the back.
Origin
C18: from pin + afore (because the term orig. denoted an apron with a bib pinned on the front of a dress).