coronal vs diadem

coronal

noun
  • A crown or coronet. 

  • The frontal bone, over which the ancients wore their coronae or garlands. 

  • A consonant produced with the tip or blade of the tongue. 

  • A wreath or garland of flowers. 

adj
  • Relating to the corona of a star. 

  • Relating to the coronal plane that divides a body into dorsal (back) and ventral (front). 

  • Relating to a crown or coronation. 

  • Relating to a sound made with the tip or blade of the tongue. 

  • Relating to the corona of a flower. 

diadem

noun
  • A crown. 

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

  • An ornamental headband worn as a badge of royalty. 

  • 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. 

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