extracurricular activity vs liaison

extracurricular activity

liaison

verb
  • To liaise. 

noun
  • 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. 

  • An illicit sexual relationship or affair. 

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