bed：A permanent structure or arrangement for sleeping on, or for the sake of rest. In some form or other it constitutes a regular article of household furniture in civilized life, as well as part of the equipment of an army or expedition. It consists for the most part of a sack or mattress of sufficient size, stuffed with something soft or springy, raised generally upon a ‘bed-stead’ or support, and covered with sheets, blankets, etc., for the purpose of warmth. The name is given both to the whole structure in its most elaborate form, and, as in ‘feather-bed,’ to the stuffed sack or mattress which constitutes its essential part.——牛津当代大辞典  @en