civil union vs marriage

civil union

noun
  • A legal union similar to marriage, established to allow same-sex couples (and, in some jurisdictions, opposite-sex couples) rights similar to those married couples have. 

marriage

noun
  • A union of two or more people that creates a family tie and carries legal, social, and/or religious rights and responsibilities. 

  • The union of two people of opposite sex, to the exclusion of all others. 

  • A close union. 

  • In solitaire or patience games, the placing a card of the same suit on the next one above or below it in value. 

  • A wedding; a ceremony in which people wed. 

  • A king and a queen, when held as a hand in some versions of poker or melded in pinochle. 

  • The state of being married. 

  • A homosexual relationship between male prisoners. 

  • The union of only two people, to the exclusion of all others. 

  • A joining of two parts. 

  • My grandparents' marriage lasted for forty years. 

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