[bu.dwaʁ], English: /ˈbuːd.wɑːr/) is a lady's private bedroom, sitting room or dressing room. The term derives from the French verb bouder, meaning "to be sulky" or boudeur, meaning "sulky".
Historically, the boudoir formed part of the private suite of rooms of a lady, for bathing and dressing, adjacent to her bedchamber, being the female equivalent of the male cabinet. In later periods, the boudoir was used as a private drawing room, and was used for other activities, such as embroidery or spending time with one's romantic partner.
~ from Wikipedia online