diadem vs turban

diadem

noun
  • An ornamental headband worn as a badge of royalty. 

  • Regal power; sovereignty; empire—considered as symbolized by the crown. 

  • A crown. 

  • An arch rising from the rim of a crown (rarely also of a coronet), and uniting with others over its centre. 

verb
  • To adorn with a diadem; to crown. 

turban

noun
  • A man's headdress made by winding a length of cloth round the head. 

  • A woman's close-fitting hat with little or no brim. 

  • The complete set of whorls of a spiral shell. 

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