coalition vs unification

coalition

noun
  • A temporary group or union of organizations, usually formed for a particular advantage. 

  • The collective noun for a group of cheetahs. 

unification

noun
  • The state of being unified. 

  • Given two terms, their join with respect to a specialisation order. 

  • The act of unifying. 

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