civil union vs wedding

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. 

wedding

noun
  • Marriage ceremony; ritual officially celebrating the beginning of a marriage. 

  • Joining of two or more parts. 

verb
  • To participate in a wedding. 

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