niqab vs purdah

niqab

noun
  • A veil which covers the face, worn by some Muslim women as a part of sartorial hijab. 

purdah

noun
  • A long veil or other attire covering most of the body, worn by women in some Muslim societies. 

  • The period between the announcement of an election or referendum and its conclusion, during which civil servants refrain from making policy announcements or taking actions that could be seen as advantageous to certain candidates in the election. 

  • A curtain, especially one used in some Hindu or Muslim traditions to conceal women from the gaze of people, particularly men and strangers. 

  • The situation or system of secluding women from the gaze of people, particularly men and strangers, in some Muslim and Hindu traditions, by using a curtain or screen, and/or wearing a face veil or attire covering most of the body. 

  • Keeping apart; isolation, seclusion; also, concealment, secrecy. 

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