a room (as in a residence) containing a bathtub or shower and usually a washbasin and toilet
"I need to wait for my roommate because she is still taking a long shower in the bathroom."
A room containing a shower and/or bathtub, and (typically but not necessarily) a toilet.
"After running late for work, I quickly splashed some cold water on my face in the bathroom before rushing out the door."
In plain English: A bathroom is a room in a house where you can wash your hands, brush your teeth, and use the toilet or shower.
"I need to find a bathroom before I leave for work."
Usage: In everyday American English, the word bathroom refers to any room containing a toilet, regardless of whether it also has a sink, shower, or bathtub. Use this term for private facilities in homes or public restrooms, even if the only fixture present is a toilet.
The word bathroom is a straightforward combination of the words bath and room. It entered English to describe a room specifically designed for bathing.