The phrase "hallway bathroom" refers to a bathroom that is located in the hallway of a building or house, rather than being directly connected to a specific room. Full definition
It is in closer proximity to the shared hallway bathroom, which would be great for guests. (amberbdesignstudio.com)
All of the guest bedrooms have queen beds; three enjoy ensuite bathrooms and two share an ample hallway bathroom. (luxuryretreats.com)
The double bunk bed room and twin room share the large hallway bathroom, which is next to the enclosed private washer and dryer. (wyndhamvacationrentals.com)