centralization vs combination

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 

combination

noun
  • The act of combining, the state of being combined or the result of combining. 

  • One or more elements selected from a set without regard to the order of selection. 

  • An association or alliance of people for some common purpose. 

  • A combination shot; a billiard; a shot where the cue ball hits a ball that strikes another ball on the table. 

  • A sequence of numbers or letters used to open a combination lock. 

  • A rapid sequence of punches or strikes in boxing or other combat sports. 

  • A motorcycle and sidecar. 

  • An object formed by combining. 

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