moon boot vs overshoe

moon boot

noun
  • A large hard plastic covering, used to protect a broken foot or ankle while it heals. 

  • A type of footwear made popular in the 1970s, with a thin rubber outsole and no distinct left or right feet. 

overshoe

noun
  • To prevent damage to a floor. 

  • To protect from water or mud. 

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