civil union vs merger

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. 

merger

noun
  • The legal union of two or more corporations into a single entity, typically assets and liabilities being assumed by the buying party. 

  • A type of sound change where two or more sounds merge into one. 

  • One that merges. 

  • An absorption of one or more estate(s) or contract(s) into one other, all being held by the same owner; of several counts of accusation into one judgement, etc. 

  • The act or process of merging two or more parts into a single unit. 

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