negligee
noun /ˈneɡlɪʒeɪ/
  /ˌneɡlɪˈʒeɪ/
(also negligée)
 - a woman’s dressing gown made of very thin clothWord Originmid 18th cent. (denoting a kind of loose gown worn by women): from French, literally ‘given little thought or attention’, feminine past participle of négliger ‘to neglect’.