Source : Webster's Revised Unabridged Dictionary (1913)

Negligee \Neg`li*gee"\, n. [F. n['e]glig['e], fr. n['e]gliger to
   neglect, L. negligere. See {Neglect}.]
   An easy, unceremonious attire; undress; also, a kind of easy
   robe or dressing gown worn by women.

Source : WordNet®

negligee
     n : a loose dressing gown for women [syn: {neglige}, {peignoir},
          {wrapper}, {housecoat}]