affair vs topic

affair

noun
  • A party or social gathering, especially of a formal nature. 

  • An action or engagement not of sufficient magnitude to be called a battle. 

  • An adulterous relationship (from affaire de cœur, affair of the heart). 

  • A person with whom someone has an adulterous relationship. 

  • A romantic relationship with someone who is not one's regular partner (boyfriend, girlfriend). 

  • Something which is done or is to be done; business of any kind, commercial, professional, or public. 

  • Any proceeding or action which it is wished to refer to or characterize vaguely. 

  • A material object (vaguely designated). 

topic

noun
  • Subject; theme; a category or general area of interest. 

  • Discussion thread. 

  • A musical sign intended to suggest a particular style or genre. 

adj
  • topical 

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