dud vs unluck

dud

noun
  • A loser; an unlucky person. 

  • A lottery ticket that does not give a payout. 

  • A failure of any kind. 

  • A device or machine that is useless because it does not work properly or has failed to work, such as a bomb, or explosive projectile. 

unluck

noun
  • Absence or lack of luck; lucklessness; bad luck; misfortune. 

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