dark blue vs woad

dark blue

noun
  • A deep, dim blue colour: navy or similar. 

  • A member of the Oxford rowing team. 

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 dark blue and woad occurred in a corpus of books? (source: Google Ngram Viewer )