neckline
noun [ C ] uk/ˈnek.laɪn/ us/ˈnek.laɪn/
领口，开领
the shape made by the edge of a dress or shirt at the front of the neck or on the chest
She wore a dress with a plunging neckline (= one showing part of her breasts). 她穿了一件V字领的低胸连衣裙。