deshabille

noun
des·​ha·​bille | \ ˌde-sə-ˈbēl How to pronounce deshabille (audio) , -ˈbil How to pronounce deshabille (audio) , -ˈbē How to pronounce deshabille (audio) \

variant of

1a archaic : negligee
b : the state of being dressed in a casual or careless style
2 : a deliberately careless or casual manner