baignoire

You mean the young lady below stairs, in a baignoire in a pink dress?

At the end of the act Newman observed that Valentin was still in the baignoire.

Newman at last made his way out, and in doing so he passed beneath the baignoire of Mademoiselle Noemie.

By this time Newman was abreast of the baignoire; the door had been left ajar, and he could see a pink dress inside.