A pinafore (colloquially a pinny /ˈpɪni/ in British English) is a sleeveless garment worn as an apron.
Pinafores may be worn by girls as a decorative garment and by both girls and women as a protective apron. A related term is pinafore dress (known as a jumper dress in American English), i.e. a sleeveless dress intended to be worn over a top or blouse. A key difference between a pinafore and a jumper dress is that the pinafore is open in the back. In informal British usage, however, a pinafore dress is sometimes referred to as simply a pinafore, which can lead to confusion.
The name reflects that the pinafore was formerly pinned (pin) to the front (afore) of a dress. The pinafore had no buttons, was simply "pinned on the front" which led to the term "pinafore.