waterbed

[waw-ter-bed, wot-er-]
noun
  1. 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. 2018

British Dictionary definitions for water bed

water bed

noun
  1. 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

Word Origin and History for water bed

waterbed

n.

1610s, "a bed on board a ship," from water (n.1) + bed (n.). As a water-tight mattress filled with water, it is recorded from 1844, originally for invalids. Reinvented c.1970 as a hip furnishing.

Online Etymology Dictionary, © 2010 Douglas Harper