separation vs tie-in

separation

noun
  • The act of disuniting two or more things, or the condition of being separated. 

  • Departure from active duty, while not necessarily leaving the service entirely. 

  • An agreement legalizing such an arrangement. 

  • An object that separates two spaces. 

  • The act or condition of two or more people being separated from one another. 

  • The place at which a division occurs. 

  • An interval, gap or space that separates things or people. 

  • The act or condition of a married couple living in separate homes while remaining legally married. 

tie-in

noun
  • An association or connection between things. 

  • Something that is related or connected to another thing. 

  • An authorized product based on a media property, such as a film or video game, by way of cross-promotion. 

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