"bathroom" in French

Even though it looks like this word is plural (i.e. referring to many bathrooms) since it ends with "s" , it is actually singular (i.e. only talking about one bathroom). The use of "s" is that this is a room for taking many baths. Note too that you may sometimes see a version of this word without an "s", salle de bain, but the version here with the "s" is the much more common form (and therefore arguably the more correct form).