Other forms: pinafores
A little girl in a British novel might wear a pinafore — a white, apron-like garment worn over a dress — but you probably won't see pinafores on the runways.
The word pinafore, designating a sleeveless child's dress worn over other clothing, has moved on from its original meaning, which can still be seen lurking in the word itself. It was originally a protective apron "pinned afore," or over, one's clothes. These days, a pinafore is primarily worn by a young girl, and in Britain it's called a pinny for short.