collude vs level set

collude

verb
  • to act in concert with; to conspire 

level set

verb
  • To establish a baseline of mutual understanding 

noun
  • An event consisting of level setting 

  • The set of values x for which a real-valued function f(x) is equal to a given constant. 

  • A state of mutual understanding among parties 

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