arguably vs incidentally

arguably

adv
  • As can be supported or proven by sound logical deduction, evidence, and precedent. 

incidentally

adv
  • By chance; in an unplanned way. 

  • In an incidental manner; not of central or critical importance. 

  • Parenthetically, by the way. 

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