fortuitously vs unintentionally

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. 

unintentionally

adv
  • In an unintentional manner; not intentionally. 

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