affair vs liaison

affair

noun
  • A person with whom someone has an adulterous relationship. 

  • 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 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. 

  • 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). 

liaison

noun
  • An illicit sexual relationship or affair. 

  • The pronunciation of a normally silent final consonant when the next word begins with a vowel. 

  • Communication between two parties or groups. 

  • Co-operation, working together. 

  • A relayer of information between two forces in an army or during war. 

  • Any person who relays information between two groups or organizations. 

  • Fusion of two consecutive words and the manner in which this occurs. 

  • A tryst, romantic meeting. 

verb
  • To liaise. 

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