housecoat vs kaftan

housecoat

noun
  • A longish dress-like garment of one piece, fastening down the front, worn about the house. 

  • A bathrobe or dressing gown. 

kaftan

noun
  • A long dress or shirt similar in style to those worn in the Eastern Mediterranean. 

  • A long tunic worn in the Eastern Mediterranean. 

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