The negligee or négligée, from the French: négligé, literally meaning "neglected", is a form of women's clothing consisting of a sheer usually long dressing gown. It is a form of nightgown intended for wear at night and in the bedroom.
Modern negligees are often much looser and made of sheer and semi-translucent fabrics and trimmed with lace or other fine material, and bows. From the 1940s to the 1970s, the trend was for negligees to become shorter in length (e.g. the babydoll)
(from wiki: http://en.wikipedia.org/wiki/Negligee)