chador vs hijab

chador

noun
  • A loose robe, made from a single cloth, worn as a combination head covering, veil and shawl by Muslim women, especially in Iran. 

hijab

noun
  • A traditional headscarf worn by Muslim women, covering the hair and neck. 

  • The practice, among Muslim women, of covering the body after the age of puberty in front of non-related adult males. 

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