The little girl wore a checkered pinafore over her dress to protect it during the picnic.

pinafore 是由 pin（别针）和 afore（在前）组成的复合词，字面意思是"用别针固定在前面的衣物"。这是一种无袖的围裙式服装，通常穿在连衣裙外面起到保护作用，常见于儿童服装。