1a room in which there is a bath/ bathtub, a washbasin and often a toiletGo and wash your hands in the bathroom.2(North American English) a room in which there is a toilet, a sink and sometimes a bath/ bathtub or showerI have to go to the bathroom(= use the toilet).Where's the bathroom? (= for example in a restaurant)
Usage note: toilet / bathroomIn British English, but not in North American English, the room that has a toilet in it is usually referred to as a toilet. This room in people’s houses can also be called the lavatory, or informally, the loo. An extra downstairs toilet in a house can be called the cloakroom. In public places, especially on signs, the words toilets, Gents (for men’s toilets) or Ladies (for women’s toilets) are used for a room or small building containing several toilets. You might also see WC or Public Conveniences on some signs.In North American English the room that contains a toilet is usually called the bathroom, never the toilet. A room with a toilet in a public place can also be called a restroom, ladies’ room, women’s room or men’s room. Washroom is also used, especially in Canada.
ˈbɑːθruːm
ˈbæθruːm
1 a room in which there is a bath/ bathtub, a washbasin and often a toiletGo and wash your hands in the bathroom. 
Usage note: toilet / bathroomIn British English, but not in North American English, the room that has a toilet in it is usually referred to as a toilet. This room in people’s houses can also be called the lavatory, or informally, the loo. An extra downstairs toilet in a house can be called the cloakroom. In public places, especially on signs, the words toilets, Gents (for men’s toilets) or Ladies (for women’s toilets) are used for a room or small building containing several toilets. You might also see WC or Public Conveniences on some signs.In North American English the room that contains a toilet is usually called the bathroom, never the toilet. A room with a toilet in a public place can also be called a restroom, ladies’ room, women’s room or men’s room. Washroom is also used, especially in Canada.