slipcover vs wrapper

slipcover

noun
  • A fitted protective or decorative cover that may be slipped off and on a piece of upholstered furniture, usually made of cloth. 

wrapper

noun
  • Something that is wrapped around something else as a cover or protection: a wrapping. 

  • An outer garment; a loose robe or dressing gown. 

  • One who, or that which, wraps. 

  • A construct, such as a class or module, that serves to mediate access to another. 

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