oilskin vs overcoating

oilskin

noun
  • A raincoat made from cotton fabric treated with oil and pigment to make it waterproof. 

  • Cloth made from cotton and treated with oil and pigment to make it waterproof. 

  • Foul-weather gear worn by sailors, whether of natural or synthetic materials. 

overcoating

noun
  • cloth for making overcoats 

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