onesie
noun [ C ] uk/ˈwʌn.zi/ us/ˈwʌn.zi/
US（婴儿穿的）连身衣
a piece of clothing for a baby that covers the whole body, sometimes including the arms, legs, and feet, and that fastens between the legs
（成人穿的）连身衣
a similar piece of clothing for adults that covers the whole body, including the arms and legs, and sometimes the feet and head. Onesies fasten at the front and are worn when relaxing.