Pinafores may be worn by girls as a decorative garment and by both girls and women as a protective apron. 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."
A related term is pinafore dress, which is British English for what in American English is known as a jumper dress, 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.
A pinafore is a full apron with two holes for the arms that is tied or buttoned in the back, usually just below the neck. Pinafores have complete front shaped over shoulder while aprons usually have no [bib], or only a smaller one. A child's garment to wear at school or for play would be a pinafore.
Further confusion results from some foreign languages, which, unlike English, do not have a distinctive term for the pinafore. In German, for example, there is no precise term for pinafore. Schürze' means "apron" and thus Kinderschürze'' is used to describe a child's apron or pinafore.
In modern times, the term "pinny" has taken another meaning in sports clothes, namely a double-sided short apron, often made of mesh, used to differentiate teams.