negligee

/ˌnɛɡlɪˈʒeɪ/
noun
  1. A woman's light, usually sheer, dressing gown or robe, often worn over a nightgown or for lounging.
    • The actress wore a lace negligee in the bedroom scene.
    • He gave her a beautiful blue negligee as a birthday gift.
    • She bought a silk negligee for her honeymoon.