A pinafore (colloquially a pinny in British English) is a sleeveless garment worn as an apron.

Pinafores may be worn as a decorative garment and as a protective apron. A related term is pinafore dress (known as a jumper 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. Nevertheless, this has led some authors to use the term "pinafore apron", although this is redundant as pinafore alone implies an apron.

The name reflects the pinafore having formerly pinned (pin) to the front (afore) of a dress. The pinafore had no buttons and was simply "pinned on the front".