fortuitously vs unfortunately

fortuitously

adv
  • In a fortuitous manner; in a manner of happening by chance; coincidentally; accidentally. 

  • In a fortuitous manner; in a manner of happening by a lucky chance; luckily; fortunately. 

unfortunately

adv
  • Happening through bad luck, or because of some unfortunate event. 

  • Used (as a parenthetical word) to express disappointment, compassion, sorrow, regret or grief. 

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