the neckline of a dress or other piece of clothing (= the shape made by the edge of it at the front of the neck) that is cut low in the middle at the front and shaped like the top of a heart

She was wearing a stunning dress with a sweetheart neckline and gently gathered skirt. 她穿着一件令人惊艳的心形领口连衣裙和轻柔的褶皱裙子。