Titanic vs doubtful

Titanic

noun
  • A venture that fails spectacularly, especially one perceived as overconfident. 

name
  • The R.M.S. Titanic, an ocean liner, supposedly unsinkable, that sank on its maiden voyage on 15 April 1912 after colliding with an iceberg. 

adj
  • Of a conflict or contest: involving equally powerful participants. 

  • Of or relating to the Titans, a race of giant gods in Greek mythology. 

  • Having great size, or great force, power, or strength. 

doubtful

noun
  • A doubtful person or thing. 

adj
  • Experiencing or showing doubt, sceptical. 

  • Subject to, or causing doubt. 

  • Improbable or unlikely. 

  • Unclear or unreliable. 

  • Suspicious, or of dubious character. 

  • Undecided or of uncertain outcome. 

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