affair vs transaction

affair

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

  • 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). 

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

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

  • A material object (vaguely designated). 

transaction

noun
  • The act of conducting or carrying out (business, negotiations, plans). 

  • A social interaction. 

  • A record of the proceedings of a learned society. 

  • An exchange or trade, as of ideas, money, goods, etc. 

  • A deal or business agreement. 

  • The transfer of funds into, out of, or from an account. 

  • An atomic operation; a message, data modification, or other procedure that is guaranteed to perform completely or not at all (e.g. a database transaction). 

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