centralization vs congregation

centralization

noun
  • The act or process of centralizing, or the state of being centralized; the act or process of combining or reducing several parts into a whole 

congregation

noun
  • The act of congregating or collecting together. 

  • Any large gathering of people. 

  • A gathering of faithful in a temple, church, synagogue, mosque or other place of worship. It can also refer to the people who are present at a devotional service in the building, particularly in contrast to the pastor, minister, imam, rabbi etc. and/or choir, who may be seated apart from the general congregation or lead the service (notably in responsory form). 

  • A Roman Congregation, a main department of the Vatican administration of the Catholic Church. 

  • A corporate body whose members gather for worship, or the members of such a body. 

  • A flock of various birds, such as plovers or eagles. 

  • The main body of university staff, comprising academics, administrative staff, heads of colleges, etc. 

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