oilskin vs poncho

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. 

poncho

noun
  • A similar waterproof garment, today typically of rubber with a hood. 

  • A simple garment, made from a rectangle of cloth, with a slit in the middle for the head. 

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