Bathroom
From Memory Alpha, the free Star Trek reference
(covers information from several alternate timelines)
A bathroom, also known as a restroom, waste extraction, toilet facility, is a room generally contains a toilet, and may also contain any of the following: sink, shower/sonic shower or a bath tub. These fixtures are then connected to a sewage and waste reclamation system where they are recycled.
In 2255 of an alternate reality, Leonard McCoy sought shelter in the shuttle Bardeen's windowless bathroom in response to his aviophobia. An officer would later escort McCoy, despite his protestations, to a seat. (Star Trek)
The microbrain from Velara III caused several malfunctions all over the USS Enterprise-D including locking two crewmembers in the programmers' restroom. (TNG: "Home Soil")
The holding cells aboard Deep Space 9 featured a restroom. (DS9: "Vortex")
In 2375, the USS Voyager faced a situation where it was functioning on a mere four lavatories. (VOY: "Bride of Chaotica!")
