futon vs sheet

futon

noun
  • A thin mattress of tufted cotton or similar material, placed on a floor or on a raised, foldable frame as a bed. 

  • A round cushion used for Zen meditation, traditionally made of woven bulrush leaves. 

  • A specific kind of sofa-bed, with a fixed cushion that forms a mattress when folded down and a sofa when folded up. 

sheet

noun
  • A thin bed cloth used as a covering for a mattress or as a layer over the sleeper. 

  • A layer of veneer. 

  • A piece of paper, usually rectangular, that has been prepared for writing, artwork, drafting, wrapping, manufacture of packaging (boxes, envelopes, etc.), and for other uses. The word does not include scraps and irregular small pieces destined to be recycled, used for stuffing or cushioning or paper mache, etc. 

  • A sail. 

  • A thin, flat layer of solid material. 

  • A line (rope) used to adjust the trim of a sail. 

  • The area of ice on which the game of curling is played. 

  • Precipitation of such quantity and force as to resemble a thin, virtually solid wall. 

  • A flat metal pan, often without raised edge, used for baking. 

  • A broad, flat expanse of a material on a surface. 

  • An extensive bed of an eruptive rock intruded between, or overlying, other strata. 

  • The space in the forward or after part of a boat where there are no rowers. 

verb
  • To form into sheets. 

  • Of rain, or other precipitation, to pour heavily. 

  • To cover or wrap with cloth, or paper, or other similar material. 

  • To trim a sail using a sheet. 

How often have the words futon and sheet occurred in a corpus of books? (source: Google Ngram Viewer )