strapless
adjective uk/ˈstræp.ləs/ us/ˈstræp.ləs/
（连衣裙、文胸等女装）无肩带的，无吊带的
A strapless dress, bra (= piece of underwear), or other piece of women's clothing does not have pieces of material going over the shoulders.
a strapless taffeta evening gown 无肩带塔夫绸晚装