waterbed

[ waw-ter-bed, wot-er- ]
/ ˈwɔ tərˌbɛd, ˈwɒt ər- /

noun

a bed having a liquid-filled rubber or plastic mattress in a rigid, often heated, waterproof frame, and providing a surface that conforms to the sleeper's body in any position.

Origin of waterbed

First recorded in 1835–45; water + bed
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for water bed

water bed

noun

a waterproof mattress filled with water

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012