What is "the powder room"?
Native speaker’s answer
Rebecca
A powder room is similar to a bathroom, but it lacks a bathtub or shower. Powder rooms have a sink and toilet like most bathrooms/washrooms have, so it's sometimes called a "half bath" or "guest bathroom." It's a place where people can "freshen up" (i.e. tidy up or put on makeup), so it was called a "powder room" in the past. Now, many people prefer to call them half baths instead. Ex: A: Katie, where's your washroom? B: There's a guest bath down the hall! Ex: This house has two bathrooms and one half bath.