Noun
A kind of mattress made of, or covered with, waterproof fabric and filled with water. It is used in hospitals for bedridden patients.
Source: Webster's dictionarywater-bed
The amount of slapstick and physical humour in storylines increased during the 1990s, with comical characters such as Reg Holdsworth and his water bed. Source: Internet
The water bed is narrow and the average drop is large, so the flow in this section is extremely turbulent and fast. Source: Internet