heroic vs unknown

heroic

noun
  • A heroic verse. 

adj
  • Courageous; displaying heroism. 

  • Of or relating to a hero or heroine; supremely noble 

  • Of a size larger than life, but less than colossal. 

unknown

adj
  • Not known; unidentified; not well known. 

noun
  • A variable (usually x, y or z) whose value is to be found. 

  • A person of no identity; a nonentity 

  • Any thing, place, or situation about which nothing is known; an unknown fact or piece of information. 

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