sectarianism vs unionism

sectarianism

noun
  • Rigid adherence to a particular sect, denomination, ideology, or party. 

  • A political system in which power is shared among religious sects based on a constitutional formula distributing public offices among these sects 

unionism

noun
  • Support for the continuance of the United Kingdom (especially with respect to Northern Ireland). 

  • The support of advocacy of a union, especially of a trade union. 

  • Support for the North (the Union) during the American Civil War. 

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