futon vs hassock

futon

noun
  • 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. 

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

hassock

noun
  • A cushion used primarily in churches for kneeling on while praying. 

  • A thick cushion used as a seat; an ottoman or pouffe. 

  • A dense clump of grass or vegetation; a tussock. 

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