housecoat

A bathrobe or dressing gown.CanadaUS

A longish dress-like garment of one piece, fastening down the front, worn about the house.Australia

• They went downstairs in their gay cotton house-coats and found Mrs Dibble in the kitchen, doddering over a lunch that required no preparation, being merely a section of ham sausage and a few pickled onions.
• Her housecoat had fallen open. She was wearing only panties and bra, which did nothing to make her scrawny, wrinkled body appealing.