cerulean vs woad

cerulean

noun
  • A greenish-blue color. 

  • Any of various lycaenid butterflies of the genus Jamides. 

adj
  • Sky-blue. 

woad

noun
  • The blue dye made from the leaves of the plant. 

  • The plant Isatis tinctoria. 

verb
  • To plant or cultivate woad. 

  • To dye with woad. 

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