An apron for a child to protect the front part of dress; a tier.

A sleeveless garment that looks like an apron, usually worn by young girls.

a sleeveless dress resembling an apron; worn over other clothing

Originally used to protect dresses from dirt, it was adopted as a fashion piece and worn as a sleeveless dress or over a blouse.

pinny [colloq.] large apron or sleeveless smock worn by adult female