Definition of pinafore in US English:

pinafore

noun

  • 1A sleeveless apron-like garment worn over a young girl's dress, typically having ties or buttons at the back.

    1. 1.1 A woman's loose sleeveless garment, typically full length and worn over clothes to keep them clean.
    2. 1.2British A collarless sleeveless dress worn over a blouse or sweater; a jumper.

Origin

Late 18th century: from pin + afore (because the term originally denoted an apron with a bib pinned on the front of a dress).

Pronunciation

pinafore

/ˈpinəˌfôr//ˈpɪnəˌfɔr/