air cushion vs mattress

air cushion

noun
  • A rubber or plastic inflatable cushion. 

  • A shock absorber that uses an air chamber. 

  • A layer of trapped air that supports a hovercraft. 

mattress

noun
  • A pad on which a person can recline and sleep, usually having an inner section of coiled springs covered with foam or other cushioning material then enclosed with cloth fabric. 

  • A form of retaining wall used to support foundations or an embankment 

verb
  • To cover with a thick layer, like a mattress; to blanket. 

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