dishabille

noun2

1. •
   Extreme casual or disorderly dress, for example, with the shirttail out, sleeves unbuttoned, etc.

   • When I rallied him for visiting me in such a dishabille, he stood a tiptoe to view himself in the glass; and owning I was in the right, said that he would go and dress himself before dinner. — 1751
2. •
   A loose, negligent dress.

   • She wore a dishabille of mignonette-green silk and bead-diapered head-dress that added several inches to her height […] — 1919